Talk:Electron diffraction/Archive 1

Archive 1

Complete overhaul needed

This article needs to be reworked quite a bit. Not only is it a stub, but some of the statements made are simply wrong. For example: "The technique is only used on crystal samples..." (no, it is also used for amorphous solids and gas molecules) and "The electrons are scattered by interaction with the positively charged atomic nuclei." (no, the electrons are scattered by both the nuclei and electrons surrounding the atom core.)

Perhaps we should try to outline a new article? A first draft could be something like this:

• Section: Wave-nature of electrons, link to article on interference of waves, link to article on general diffraction. Formula for wavelength of electrons as function of accelerating voltage. How are electrons scattered? Differences and similarities with photons (X-ray) and neutrons.

• Section: how is electron diffraction used in crystal structure determination? In studies of amorphous solids? In studies of gas molecules? An alternative would be to rewrite the electron crystallography article (probably better, and should probably be done anyway).

• Section: Geometry of electron diffraction in transmission

• Section: Geometry of electron diffraction in backscattering

• Section: Geometry of gas-electron diffraction

My experience is almost exclusively with electron diffraction in TEM and I'm going to need some help with the structuring and writing of this article!

oysteinp

First sketch

(October 19 2005 (oysteinp), modified October 20 (oysteinp), October 23 (oysteinp))

Could this work as a start?

Electron diffraction is a technique used to study matter by firing electrons at a sample and observing the resulting interference pattern. This phenomenon occurs due to the wave-particle duality, which states that a particle of matter (in this case the incident electron) just as well can be described as a wave. The electron is then diffracted in a similar fashion as classical waves such as sound or waves in water. This technique is similar to X-ray diffraction and neutron diffraction.

Electron diffraction is most frequently used in solid state physics and chemistry to study the crystal structure of solids. The periodic structure of a crystalline solid acts as a diffraction grating, scattering the electrons in a predictable manner. Working back from the observed diffraction pattern, it may be possible to deduce the crystal structure giving rise to that particular pattern. However, the technique is limited by the phase problem.

Apart from the study of crystals, electron diffraction is also a useful technique to study the short range order of amorphous solids, and the geometry of gaseous molecules.

Theory The wavelength of an electron is given by the de Broglie equation

$\lambda ={\frac {h}{p}}$

Here $h$ is Planck's constant, $p$ the momentum of the electron and $m_{0}$ its mass. The electrons are accelerated in an electric potential $U$ to the desired velocity:

$v={\sqrt {\frac {2eU}{m_{0}}}}$

The electron wavelength is then given by:

$\lambda ={\frac {h}{p}}={\frac {h}{m_{0}v}}={\frac {h}{\sqrt {2m_{0}eU}}}$

However, in an electron microscope, the accelerating potential is usually several thousand volts causing the electron to travel at an appreciable fraction of the speed of light. An SEM may typically operate at an accelerating potential of 10.000 volts (10 kV) giving an electron velocity approximately 20% of the speed of light, while a typical TEM can operate at 200 kV raising the electron velocity to 70% the speed of light. We therefore need to take relativistic effects into account. It can be shown that the electron wavelength is then modified according to:

$\lambda ={\frac {h}{\sqrt {2m_{0}eU}}}{\frac {1}{\sqrt {1+{\frac {eU}{2mc^{2}}}}}}$

We recognize the first term in this final expression as the non-relativistc expression derived above, while the last term is a relativistic correction factor. The wavelength of the electrons in a 10 kV SEM is then 12.3 x 10^-12 m (12.3 pm) while in a 200 kV TEM the wavelength is 2.5 pm. In comparison the wavelength of X-rays usually used in X-ray diffraction is in the order of 100 pm (Cu kα: λ=154 pm).

• How are electrons scattered?
• Differences and similarities with photons (X-ray) and neutrons.

Electron diffraction in the TEM

Sketch of the electron beam-path in a TEM.

Electron diffraction of solids is usually performed in a Transmission Electron Microscope (TEM) where the electrons pass through a thin film of the material to be studied. The resulting diffraction pattern is then observed on a fluorescent screen or recorded on photographic film or a CCD camera. In the TEM, electron diffraction can be combined with a range of other techniques such as chemical analysis of the sample composition through energy-dispersive X-ray spectroscopy, direct imaging of the sample, including high resolution imaging of the crystal lattice, electron energy loss spectroscopy, and electron holography.

Geometry of electron diffraction in backscattering

Geometry of gas-electron diffraction

TEM-sentric

(23 October 2005, oysteinp) The article sketch I've posted above is becoming a little TEM-sentric. I'm sure there are lots of people out there that could add info om other forms of electron diffraction!

Why don't you just edit the article directly? You seem to know what you are talking about, don't be timid. linas 06:58, 22 November 2005 (UTC)

Well, ok. I just thought it would be a good idea to discuss the content of the article :) But anyway: I've updated parts of the article. I'll work some more on it later. O. Prytz 21:09, 22 November 2005 (UTC)

For highly contentious articles, where many people are arguing over many things, that would be a very good, and polite, thing to do. This article, by contrast, suffers from neglect: no one is bothering much to edit it, and so there won't be much of a discussion, either. As long as you are ot adding patent non-sense, you'll have free reign. linas 00:12, 23 November 2005 (UTC)

I've written a bit more in the section on electron interation with matter, it's mostly a comparison of the different forms of interaction applicable to electrons vs. neutrons vs. X-rays. Could anyone have a look at this? I'm a bit uncertain about the details of this section and it would be good if someone could check the validity of the statements. O. Prytz 20:44, 6 December 2005 (UTC)

Done. Only the strong interaction counted for the nuclear force. I simplified the x-ray sentance. linas 04:55, 7 December 2005 (UTC)

I've added a section on electron diffraction in a TEM, a couple of figures and a reference. O. Prytz 14:45, 18 December 2005 (UTC)

New section

I've added a new section on the intensity of diffracted electron beams. It's not quite done yet. But the real question is really: how detailed should a Wikipedia article be? I mean: you could write a textbook if you like, but is that really appropriate?O. Prytz 13:05, 21 December 2005 (UTC)

I've fleshed out the Electron diffraction in TEM section a bit with a discussion of the benefits of this technique. I'll add a section on limitations later. Once againg I'm worried that the article may become a little too detailed and focused on TEM. Furthermore, maybe some of the content should be moved to the electron crystallography article (which really needs some work). O. Prytz 10:13, 31 December 2005 (UTC)

Done for now

Ok, I finished the section on limitations, but I'm afraid it's prettey POV so please have a look and rewrite/delete anything not belonging in an encyclopedia. I'll be adding some refrences to the article sooner or later... I'm still a bit worried that the article gives undue weight to electron diffraction in TEM. I might eventually move some of the content to electron crystallography which needs a bit of work. O. Prytz 19:20, 2 January 2006 (UTC)

Thanks! For the most part, it looks pretty good. You might also consider starting a new article electron diffraction in TEM, maybe. Or maybe nt. Eithre way, thanks. linas 21:09, 3 January 2006 (UTC)

Hm...that might be a good idea, although I think I'll wait until I've had a go at electron crystallography. O. Prytz 20:31, 4 January 2006 (UTC)

TEM centric

It's TEM centric because electron diffraction can be done on most any TEM, while it's not often done on an SEM. Why is the wavelength of the electron in an SEM so prominent and first when electron diffraction in an SEM is hardly touched upon? The order should be changed to reflect that the article includes extensive information about TEM electron diffraction, not SEM. --Blechnic (talk) 06:44, 28 May 2008 (UTC)

Assessment comment

The comment(s) below were originally left at Talk:Electron diffraction/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

Seems like an okay article, but it needs more references first of all Snailwalker | talk 14:13, 19 October 2006 (UTC)

Last edited at 14:13, 19 October 2006 (UTC). Substituted at 14:19, 29 April 2016 (UTC)

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Article rating after substantial transform

Dear fellow Wikipedians,

the article has undergone a substantial transform in recent weeks (before and after) and I hope its rating became out-dated. If I understand it well, the rating can only be changed manually. If you agree the B is out-dated, could you please help me with changing it appropriately?

Similarly, there is an article about Selected area diffraction which I hope is not a Stub any more and another one about CrysTBox which has not been rated at all.

Thank you very much for your help.

Klingm01 (talk) 18:07, 7 March 2022 (UTC)

This article needs major work

This article, at least in it's current form, contains major errors of science. There are also some grammatical issues, although these are less severe Ldm1954 (talk) 11:18, 18 January 2023 (UTC)

Please fix it and include references for your additions / corrections. Regards, Ariconte (talk) 20:27, 18 January 2023 (UTC)

Thank you for your willingness to improve the article. However, deleting the whole Theory section (incl. all images, tables and formulas) is definitely not the best way. I'm not saying the section is perfect, but formulas and tables taken from the literature (see the references) are definitely not scientifically wrong neither are images showing the relation between spot and ring diffraction or what Kikuchi lines are. I hope that gradual edits (like those you have yourself made in this very section before deleting it) are much better way to improve the article. --Klingm01 (talk) 12:22, 4 February 2023 (UTC)

As someone who has taught the topic for decades, and extensively published I will tell you the section is awful, and misleading:

1. The non-relativistic wavelength form is never used.

2. The relativistic form is incorrect, as an effective mass is used to cancel some terms (see Hirsch et al or Peng, Dudarev & Whelan).

3. The statements/equations about kinematical theory are completely wrong -- there is a |sin(pi*t*sz)/(pi*sz)|**2 missing.

4. The "effects of crystallinity" is misleading, for instance double diffraction is ignored

5. As written the Kikuchi line section does not belong in this section. To do the theory properly Bloch waves have to be introduced first, which would be a large digression.

6 The gas phase section is also not theory.

While I understand that you want to give people a simple explanation so they can use simple codes, that takes knowledge backwards. The whole theory section must be removed. Electron diffraction is not simple.

Ldm1954 (talk) 11:22, 7 February 2023 (UTC)

Please, stop vandalizing the article

Lets's be minimalistic. Dear Ldm1954, feel free to continue with personal offenses and humiliations, feel free to improve the article, but please stop vandalizing it. After your edits, there are errors, empty sections, references to removed images, not mentioning the content. Klingm01 (talk) 14:58, 7 February 2023 (UTC)

The prior version would fail any decent TEM class at a strong university. Sorry, but that is reality. It is not "personal offenses", this is scientific rigor.

The current version is adequate, although I would still only give it a B-. I have to go and teach TEM, and will add more references later and further clarifications -- they are needed. Ldm1954 (talk) 16:06, 7 February 2023 (UTC)

Unsourced comments added

User:Ldm1954 has made a large number of unsourced edits, the user still doesn’t seem to understand how Wikipedia works. Adding comments here [1] with no sources. Theroadislong (talk) 18:56, 26 February 2023 (UTC)

The statement by Theroadislong is inaccurate. The relevant information is within a sentence or less of every statement that was added. Everything has stated sources.

User:Theroadislong, an apology would be appropriate.

Ldm1954 (talk) 19:16, 26 February 2023 (UTC)

Adding content AFTER a source is not how we do it, if the edit was covered by a previous source then the source should have been repeated. Theroadislong (talk) 21:15, 26 February 2023 (UTC)

User:Theroadislong the source was in the sentence before or the same paragraph, and clearly indicated. Please admit error. Ldm1954 (talk) 21:28, 26 February 2023 (UTC)

Ldm1954, do stop vandalizing the article

Dear Ldm1954, your expertise is most welcome. Instead of using it to disparage others and their contributions, please use it to improve the article. As mentioned before, the article is not necessarily perfect, but this does not mean, you can freely remove its substantial parts without providing better alternative.

Repeated removal of substantial content and claims of incorrect information

Above, you claim the "relativistic form is incorrect" and you say

"While I understand that you want to give people a simple explanation so they can use simple codes, that takes knowledge backwards. The whole theory section must be removed. Electron diffraction is not simple."

You have removed all the formulas claiming they were wrong and too simple. What have you left there instead? Nothing. Your repeated removal of Theory section leaves an impression that there is no theory behind the diffraction. This is what "takes knowledge backwards".

Moreover, you claim the relativistic wavelength formula and/or table to be incorrect. I have just checked the formula in the article and it equals to the one stated in Prof. Kirkland's book (see the references). If there is a mistake, please fix it in the article and inform Prof. Kirkland accordingly. If there is a mistake in the wavelength table, please tell us where. Carter&Williams, Karlík, de Graef - I have just checked their books and they all state exactly the same values you have deleted for being incorrect.

Article structure

The structure of the article had its purpose:

1. History
2. Theory - Non-relativistic, relativistic, material structure (singe/poly-crystal) etc.
3. Applications - TEM (SAED, CBED etc.), SEM, Gases

This structure guided the reader from the History (from the first experiments up to de Brogile), then via the Theory (the reader could read the de Brogie's formula mentioned in the history, see its place in theory, via non-relativistic to the relativistic etc.), showing the impact of material structure on the diffractogram (single- vs. poly-crystal). The the Applications decribed TEM (it's importance from ED point, the beam and image formation, and individual experimental techniquies like SAED or CBED etc.), followed by SEM and gases.

As you know, the strengths and traps of the diffraction imaging originate from the fact, that the image is formed by so many factors at once - if we stay very simple, it's material structure, beam parameters and detectors. Please note here, that the original structure kept those factors separated instead of mixing them all together. This is crucial for understanding the influence of the individual aspects on the resulting diffraction.

Please note also, that the structure allowed the article to be read in whole (with a continuous flow and gradual information develpment) as well as in parts (individual subsections as self-supporting as possible).

After you "rationalized" the structure we have:

1. History
2. Types of electron diffraction

In the giant, unstructured section called Types of electron diffraction, you put together different instrument, phenomena or techniques with no respect to their functional or causal relations. At the same level in one single section, you mix together

• experimental instruments (TEM, SEM, RHEED)
• experimental techniques (CBED, 4D STEM, Precession etc.)
• material structure (singe- vs. poly-crystalline samples)
• general information specific to TEM (formation of image in TEM)
• theory (double diffraction)
• diffractogram features (Kikuchi lines)

This looks as if the Scanning electron microscope shared the category and level with Kikuchi lines. This is extremely confusing. Of course, experts can orient themselves in this chaos, but beginners or cross-disciplinary people will be lost and confused. And this is encyclopedia - it should be readable for a broader audience.

Summary

These are just the major areas of arguments qualifying your activities as vandalism. I am not mentioning particularities like that you should prepare your edits in your sandbox instead of continuously editing the article visited by the readers meanwhile or that the non-realistic wavelength, which is mentioned in all relevant books, is relevant here, it allows to bridge the History and Theory and it's extent is proportional.

Please, do not repeat your vandalizing activity. As mentioned repeatedly, you are welcome to improve the articles. Try to focus on smaller, gradual changes. This does not mean, however, removing each Theory subsection individually (12:23, 7 February 2023‎ and later) instead of removing it at once (19:13, 2 February 2023). It means correcting particular mistakes as you spot them and can prove them. Before more substantial edits, feel free to contact the original authors or discuss them here on the talk page.

Your knowledge is needed, but use it constructively.

Klingm01 (talk) 12:56, 8 February 2023 (UTC)

Reactions

I will give you a hint, have a look at https://scholar.google.com/citations?user=zmHhI9gAAAAJ

Also, please say hello for me to Marianna, and ask if I will see her at IMC20 in September. Ldm1954 (talk) 16:01, 8 February 2023 (UTC)

I posted this on my talk page, I will repeat it here:

I am afraid that you have misunderstood. The full formulation for the energy and mass is standard and can be found in main sources such as HHPNW & JMC. Scientific rigor says cite the key early papers/books, not later ones. For instance from my class notes (you will find it elsewhere as well):

"The total energy is

Et2 = c2p2 +mo2c4

where mo is the rest mass of the electron, c the speed of light and Et is the sum of the rest energy and the kinetic energy of the electron, i.e.

Et = eE + moc2

The relativistically corrected mass to use is

m = mo + eE/2c2

(this is not the true mass of the electron, which is m0+eE/c2, but instead a value used to eliminate the relativistic terms)."

There is no real reason to go into this in the page, or the original Archie Howie explanation of how to reduce the Klein-Gordon/Dirac to the Schroedinger that is normally used in multislice/Bloch waves. (I intend to add selected refs)

For reference Marc's theory is strong, Earle's is good on multislice although I prefer the original work of Mike O'Keefe. I learnt a lot of my multislice theory from Mike O'Keefe over tea breaks back when my hair was black. Ldm1954 (talk) 15:20, 8 February 2023 (UTC)

Ldm1954 (talk) 15:28, 8 February 2023 (UTC)

You're avoiding the answer because you took on yourself a very difficult task. Showing incorrectness of something which is correct is quite difficult.

You're standing alone against all these heavy weights of electron crystallography: Kirkland, Egerton , Carter&Williams, De Graef... how many names do you need?

References

Let me remind you your own words: "Self criticism is an art not many are qualified to practice", Joyce Carol Oates

Klingm01 (talk) 16:37, 8 February 2023 (UTC)

To repeat, your formulation was incorrect.

The equations in those texts are almost certainly right.

However, the wavelength is not theory, and what was there was very much not kinematical. There is certainly no place in this section for the full Green's function derivation, e.g. http://www.numis.northwestern.edu/460/Notes/kinematical.docx or Hirsch et al. Ldm1954 (talk) 16:45, 8 February 2023 (UTC)

"Also, please say hello for me to..."

...OK so now you're even threatening me with my boss. OK... Klingm01 (talk) 16:46, 8 February 2023 (UTC)

When I said "say hello" that is what I meant.

N.B., my identity is somewhat obvious and I just edited my home page. Ldm1954 (talk) 16:57, 8 February 2023 (UTC)

Ooops! The whole theory section is gone! That was the only place in the whole English Wikipedia that stated it at that level of detail, and I miss it. As far I can say, it was fully correct once contrasted all my available sources. I can't understand Ldm1954 when he says: However, the wavelength is not theory[...] (???) For sure it was theory, and it was only theory since De Broglie to Davisson. And it was non-relativistic at first. Once confirmed, it saw a quick development, of course. I agree with Klingm01's original vision for the article, as it was it was a perfect starting point to everyone interested on such development's history.

And it is a very interesting case in history of physics, one of the few where correct theories aforehead facts. Electromagnetic theory by Maxwell predicted electromagnetic waves produced by Hertz. Mass-energy equivalence theory by Einstein ultimately lead to nuclear power plants and weapons. And we all here know De Broglie anticipated electron microscopy (to be succint). Will you, Ldm1954, mutilate those "dated theories" in the corresponding articles? Then you can delete all Ptolomy related articles as well. Even Kepler's and Newton's formulations are all outdated by today's knowledge. Strip away them all from Wikipedia!

But I'm surprised the most with your notes: The relativistically corrected mass to use is m =m₀ + e_E/2c² (this is not the true mass of the electron, which is m₀+e_E/c², but instead a value used to eliminate the relativistic terms). How you derived this? I assume e_E = m/c² – m₀/c² here, as per E_t = e_E + m₀c², so, Where that "corrected mass" came from? I've never heard on this, although it means nothing, of course, Wikipedia is meant to teach people about things like this, and I want to learn the more. And, How that "corrected mass" influences the wavelength? By using non-relativistic De Broglie, maybe, as that value "elimitate relativistic terms"?

Please, can some editor re-state the whole theory section as it prevously was? And then, may Ldm1954 or whoever extend it with appropriate material to explain about "corrected mass", and how it is used to compute wavelength. Thank you. 37.134.90.176 (talk) 08:43, 13 February 2023 (UTC)

For completeness, the relevant references and explanation are now included. The original Bethe paper in 1928 was non-relativistic, based upon Scroedinger's equation. The paper by Fujiwara in 1961 & the note by Howie in 1962 are the standard references on how relativistic diffraction is converted to non-relativistic using an effective mass -- the form is in the revised page. All of the hundreds of papers on swift electron diffraction use this fact, although it is very rarely mentioned; the Fujiwara paper has been, according to Google Scholar, only cited 176 times. Ldm1954 (talk) 14:33, 15 February 2023 (UTC)

You, Ldm1954, do not state the units for k wavevector. As per "The wavelength of the electrons is 1/k", the reader must to deduce by him/herself k is given in m^–1. Also, you do not say what eE stands for. As it is spelt, it seems it is the product of elementary charge e, which is mentioned (or even the e number as per the exponential function also mentioned) and some energy E, which is quite confusing to the reader.

But eE (or better, E_e here, for "electron energy") comes from the difference of E_t, "total energy", minus E₀, or energy equivalent of the electron rest mass m₀, that is, E₀ = m₀c². So, E_e = E_t – E₀, as per your notes E_t = E_e + m₀c², then E_t = E_e + E₀. Right?

Well. From your notes again, E_t² = c²p² + m₀²c⁴, which is OK (c·p is given in Joules). Then, E_t² = c²p² + E₀². As E₀ and c are constant (as m₀ is), the variable here is p, the kinetic momentum of the electron as a particle of a given mass. The momentum is function of velocity v, so that mass must have been accelerated to attain that velocity. How the electron has been accelerated, in first place?

Of the many ways an electron can be accelerated, De Broglie choose the energy the electron gets when under a given potential V, that is, E = e·V, being here e the elementary charge. This is how an electron gun works, Right? Asuming non-relativistic mechanics, that energy E is the classic kinetic energy, E_k = ½mv², which is a good approximation for low voltages. But assuming relativistic mechanics, it is c·p, so c·p = e·V, and thus E_t² = E₀² + e²V². From here on, the theory follows all what you, Ldm1954, have stripped out.

As you left it, there is no way for the reader to know how to compute 1/k (the wavelength λ, the magnitude we're interested to get) from the applied voltage V. Plus, you're using k as an input value, not the output one.

Conclusion: the former theory section must be re-stated at least as an introductory reasoning. Then, that "effective mass adjusted to cancel out the relativistic terms" can be addresed, if necessary, but in such way k being the resulting, deduced value. 37.134.90.176 (talk) 21:40, 17 February 2023 (UTC)

Thankyou for noting the typo, which is now corrected.

Please read the work by Fujiwara (1961), that of Howie (1962) and also other papers such as the more recent Watanabe et al (1996) cited. All electron diffraction theory start from either the Dirac equation or Schroedinger with the effective mass. They do not start with the work of De Broglie, they start with quantum mechanics. Sorry. Ldm1954 (talk) 23:49, 17 February 2023 (UTC)

Dirac's equation (1928) derived from Schrödinger wavefunctions (1925-1926) for (non-relativistic) both planar waves (leading to Klein–Fock–Gordon equation, 1926) and the hydrogen atom, which in turn extend De Broglie's hypothesis (λ = h/p, 1924) and his hydrogen atom's model (electron as stationary wave with λ_n = 2πna₀, being n the principal quantum number, with n ∈ ℕ), which in turn explain Bohr's hypothesis (1913) of quantized states and angular momentum of the hydrogen atom (L_n = m₀r_nv_n = nh/2π), to be succint. So yes, De Broglie's work IS quantum mechanics, check the years. In fact, the starting point of quantized wave mechanics was De Broglie, not Schrödinger. This is stated in every high school physics' book since then, and elsewhere here in the Wikipedia, of course.

I agree De Broglie himself didn't anticipate electron diffraction (as he didn't anticipate the electron microscope, to say), but the famous Davisson–Germer experiment (1927), the first evidence of the particle-wave duality postulated by De Broglie, was by the discovery that electrons diffract for real, which it is possible only if accelerated electrons behave as De Broglie said. This is the key link.

After your last edit, there are now two flaws:

• By substituting m^eff in the first of the two equations involving E and m^eff (BTW, I would prefer a subscript for m_eff), being here E = e·V Joules and the wavelength λ = 1/k, one reach finally ${\frac {1}{k}}=\lambda ={\frac {hc}{\sqrt {eV(2m_{0}c^{2}+eV)}}}$ (try it by yourself), which is exactly the same conclussion in the former "theory" section, "Relativistic" sub-section, that what you say it is "wrong". It's not (or if yes, yours too).
• You stated that E is typically given in electronvolts (eV), but the shown formulae are for energy in Joules (SI). This only gets the unaware audience more confused.

The main conclusion here is that, essentially, you've vandalized the whole article, as me and others complain about. Your exposition is not superior than previous, so please desist. 37.134.90.176 (talk) 02:32, 18 February 2023 (UTC)

Unfortunately you are still missing the key point. Let me try and explain it differently.

Yes, De Broglie's work was important. Nobody has ever said it was not.

However, it is not central to 21st century understanding of electron diffraction. The key paper is by Bethe (1928), as cited in the article and in articles/textbooks on dynamical diffraction. He starts with the non-relativistic Schroedinger equation, from which by assuming plane wave solutions he derives the basic form of the secular equations for a periodic potential and reciprocal lattice. He even has mean inner potential effects and aspects of the dispersion surface.

The effective mass is how the errors in the Schroedinger equation are handled for elastic scattering. (Inelastic is different.) This is the foundation of all modern methods such as multislice and channeling. The wavelength has some relevance, but is not in fact a constant inside a solid, as we know from band structure -- but this is well, well beyond what is relevant here.

Please read Bethe's paper. Sorry, but this matters. Ldm1954 (talk) 03:45, 18 February 2023 (UTC)

Addendum: I have added back the equation for the wavelength. I don't think it is useful, but Klingm01 thinks it is. It is not an important change. Ldm1954 (talk) 04:17, 18 February 2023 (UTC)

Still far from being satisfactory, specially for introducing the topic to a broader audience and students. It seems you only address those who already know about the subject. The article is not about 21st century understanding of electron diffraction only, you know.

• De Broglie's key formula, $\lambda =h/p$ should be cited, at least, along with his original non-relativistic deduction of the wavelength for electrons accelerating under a potential V, with $E_{K}=e\cdot V$, leading to $\lambda ={\frac {h}{\sqrt {2m_{0}eV}}}$, and noting this is a good approximation only for low voltages, of about 100V or so.
• The general, relativistic formula can be summarized as follow: given in special relativity both:

$E_{t}=m_{0}c^{2}+E$ and $E_{t}={\sqrt {m_{0}^{2}c^{4}+p^{2}c^{2}}}$

for the total energy $E_{t}$ of a single electron, then

$m_{0}c^{2}+E={\sqrt {m_{0}^{2}c^{4}+p^{2}c^{2}}}$.

By squaring, cancelling the resulting $m_{0}^{2}c^{4}$ at both sides and extracting $E$ as common factor at left side,

$E(2m_{0}c^{2}+E)=p^{2}c^{2}$.

As per De Broglie, $\lambda =h/p$, so $p=h/\lambda$. By substituting $p^{2}$ and solving for $\lambda ^{2}$ we get:

$\lambda ^{2}={\frac {h^{2}c^{2}}{E(2m_{0}c^{2}+E)}}$. (1)

With $E=e\cdot V$, electron wavelength is

$\lambda ={\frac {hc}{\sqrt {eV(2m_{0}c^{2}+eV)}}}$.

• The original table of wavelengths by potential, which is fully correct, should be restored.
• Notice: if $E$ is given in electronvolts, then one must use $m_{0}c^{2}\approx 0.511$ MeV, not joules.
• To the wavefunction: continuing from (1), lets introduce a convenient value $k={\frac {1}{\lambda }}$, and extracting $2c^{2}$ as common factor in the divisor:

${\frac {1}{k^{2}}}={\frac {h^{2}}{2E(m_{0}+{\frac {E}{2c^{2}}})}}$.

Lets introduce a new convenient value $m^{*}=m_{0}+{\frac {E}{2c^{2}}}$, sometimes called the electron "effective mass" by some authors [refs here]. Note this value is a shorthand akin to concepts like the reduced mass for solving the two-body problem, or the Lorentz factor in special relativity, not a true physical magnitude.

Then, by substituting with $m^{*}$ and solving for $E$:

$E={\frac {h^{2}k^{2}}{2m^{*}}}$.

And etc., up to $\psi (r)$, showing $k$ is the so-called wavevector.

This way, the full historical path is shown step-by-step, giving the complete picture without too much overload. Then you can discuss diffraction formulae next.

Plus, wavelength IS relevant to understand how accelerated electrons reach the sample where diffraction occurs. If not, there would be no difference as if discussing pure X-rays diffraction here. 37.134.90.176 (talk) 02:22, 23 February 2023 (UTC)

Please check the established literature

To repeat, please read the seminal paper by Bethe (1928) in order to understand more about the foundations. This is the established explanation, and starts from the Schroedinger equation, not the De Broglie relationship. It appeared within months of the experiments. Indeed, if you look at the original experimental papers (cited in the document) you will see that they hedge between using the De Broglie approach, and what was call undulatory mechanics, what we now call quantum mechanics or wave mechanics.

Also, please read up on effective mass using, for instance, Ashcroft and Mermin and semiconductor theory. It is far from what you are suggesting, and has real physics behind it, for instance holes in solid-state physics. It is not close to reduced mass or similar. Strictly speaking it is a tensor $h^{2}/m_{ij}^{*}=d^{2}E(k)/dk_{i}dk_{j}$, but we can simplify to $h^{2}/m^{*}=d^{2}E(k)/dk^{2}$ except in elements of dynamical theory -- but this is a big digression.

Maybe an example will help. We all know about shock waves and sound, also the sound waves in solids which are called phonons. These are collective oscillations of atoms, and can be described as both particles and waves. They have mass, which is not that of individual atoms but an effective mass as mentioned above. Almost every on has an effective mass, for instance plasmons, magnons -- see List_of_quasiparticles. Tricky physics which is beyond the scope of this article IMHO. Ldm1954 (talk) 03:12, 23 February 2023 (UTC)

Electron diffraction on crossroad

The article seems to divert from important Wikipedia standards.

Instead of addressing particular problems with the article content and structure, let me mention something more fundamental - the conflict I see between the recent direction of this article and general philosophy of Wikipedia.

This is encyclopedia

Dear Ldm1954, I do respect your expertise, but this is not a textbook, this is not your lecture, this is not your show. This is encyclopedia.

The purpose is not to generate as much content as possible, but to explain things in a generally understandable way.
The purpose is not to show off our expertise and burry the reader under an avalanche of advanced physics, but to make it understandable to broader audience with expectable amount of their effort, time and expertise.
The purpose is not to scare the readers but to attract them. Not to discourage them even from reading Wikipedia article but to show them "hey, it's not a rocket science... YOU CAN make it, YOU WILL make it" and then to encourage them to look for more... Not to build a cliff in front of them, but to offer them a staircase.

Wikipedia is not here for you, it is not here for me, it is here for the reader.
It is not about you, it is not about me, it is about the reader.

Wikipedia is a living organism

Dear Ldm1954, as mentioned above, Wikipedia is not a textbook. Printed textbooks do not change very often. Wikipedia does. And, in fact, it is one of its fundamental strengths. Please do realize, however unacceptable it might sound to you, that you are not the last author of this article. If any other author wants to add an image for instance, they will be forced to re-number all the figures and references below the added image. If any other author wants to add an image between the first and second one (as you call them Figure 1 and 2), they would need to fix the numbering at almost 60 places across the whole article. I don't know if this is your way how to intentionally cement the article in the shape you've got it into, but this is definitely not the way how the things are done here.

You're also breaking the convention of how bold text is used - it is definitely not used to emphasize "Figure 18". Personally, I do not fully agree with how bold text is (or rather isn't) used on Wikipedia either, but I do respect it. Ldm1954, please do stop with offenses and threats and start observing and listening.

The crossroad

Dear editors and readers,

It seems to me the article have reached a crossroad. However I respect Ldm1954's expertise and effort, he has overwritten the article in spite of numerous objections regarding the structure, content, sources etc. I hope this have lead the article far from Wikipedia standards and legitimate expectations of the readers. Since I can be biased, I would like to ask you for your opinion.

Please help us to find the best way - express your opinion and suggest how the article should look like:

1. Take a look at the original version of the article, current version and perhaps the discussion above.
2. Express your opinion not limited to the scientific point of view.
3. If you don't find the present state ideal, then please suggest how the article should (or should not) look like, what it should (or should not) contain and potentially how the desired state should be reached.

Thank you.

Dear readers, please note you can participate in the discussion without being Wikipedia editors.

Dear Ldm1954, since we both can be biased, I am sure you will agree it is best for you (Ldm1954) and me (Klingm01) to abstain from the discussion (feel free to react to my post in Reactions, however). I would also ask you not to edit the article until this is resolved.

Klingm01 (talk) 10:10, 2 March 2023 (UTC)

For the record

Dear User:Klingm01,

I have asked you numerous times in this overlong thread to read the literature, which will clarify your questions. I have also suggested some positive additions such as Ewald sphere; since you did not respond I have already included that for TEM, LEED & RHEED.

I realise that you put effort into a version, but it had serious issues. Wikipedia articles have to be correct, they should not contain major errors of science. Equally important they need to be properly cited, both in terms of who did what as well as when points are made (as User:Theroadislong has mentioned).

I do not want to inflame this further, but at the same time it is worth detailing some of the main issues with the version as of the end of 2022:

General

• Contains 20 cites, compared to 135 in the revised version.
• Frequently cites the software of User:Klingm01, not that of others.
• Focuses mainly on selected area electron diffraction. While this is useful it is only a small part.
• Contains many, many errors in citations, for instance the book by Fultz and Howe is missing Jim Howe (there are others).

History

• Omitted Faraday, Julius Plücker. did not correctly identify the image as a Crookes tube, Stoney.
• Misrepresented de Broglie's work -- please read his thesis.
• Omitted Schrödinger whose importance de Broglie recognised (see quote in current version).
• Incorrect credit to original electron diffraction experiments, gas diffraction and who invented the electron microscope (authors missing and not properly cited).
• Stops in 1932, and does not mention anything more.

Theory

• Incorrectly states that electrons just interact with the positive nucleus.
• Confuses combined elastic & inelastic, they occur simultaneously and cannot be separated (Copenhagen interpretation).
• Omits relativistic effective mass -- critical
• Incorrectly states that only Bragg diffraction occurs (Figure and angle).
• Gives incorrect equation for kinematical diffraction, omitting temperature factors and depth/excitation error dependence.
• Incomplete sources cited for Kikuchi
• No sources for GED

Applications

• Confused statement about Ewald sphere introduced without explanation or citation.
• No cites to other methods.
• No cites to electon optics.
• Omits LEED
• Omits RHEED
• Omits PED
• Omits electron crystallography (no cites) to solve structures.

I think it is better to move forward. At present the page is missing good experimental examples of double diffraction, superstructures, incommensurate structures and diffuse scattering. While these should not be vast, they are important and merit a paragraph. Please focus on these rather than the wavelength.

For refence, I suggest looking at X-ray crystallography (which is perhaps too long, as others have said) for comparison and as a guide. — Preceding unsigned comment added by Ldm1954 (talk • contribs) 13:26, 2 March 2023 (UTC)

Article opinions and suggestions (no Klingm01, no Ldm1954)

I have no opinion on the content of the article, it is mostly incomprehensible to an arts based layman like myself, however I do agree that the use of numbered figures should be removed, that is not how we use illustrations in articles. Theroadislong (talk) 13:24, 2 March 2023 (UTC)

The problem is that some of the Figures require cross-referencing at different locations. Removing bold is not an issue, but do you have a solution for that? Ldm1954 (talk) 13:28, 2 March 2023 (UTC)

Please provide a cite to your statement "the use of numbered figures should be removed, that is not how we use illustrations in articles". When I read the Wikipedia information nothing is stated. Ldm1954 (talk) 21:24, 3 March 2023 (UTC)

In 16 years of editing here, I've not seen this method used and it doesn't seem necessary here. Theroadislong (talk) 21:37, 3 March 2023 (UTC)

I have seen it in some other pages, admittedly a minority. As just one example, Figures 6, 17 and 19 are all Ewald sphere constructions of different types, relevant both to the general discussion within Geometry of diffraction and the more specific LEED and RHEED sections. This is technically correct. On non-technical issues I will defer to your expertise, but not on technical ones such as this. Ldm1954 (talk) 21:43, 3 March 2023 (UTC)

Ok, it's a mess but if you think it is required, I will not argue further, it will be a nightmare for anyone adding further images in future. Theroadislong (talk) 21:54, 3 March 2023 (UTC)

Topic expert

User:Ldm1954 you may be a topic expert, BUT we still require references for any content that you add. Theroadislong (talk) 17:29, 13 May 2023 (UTC)

They are already there. Ldm1954 (talk) 17:35, 13 May 2023 (UTC)

You may consider it "pedantic", and tiresome, but it is absolutely required that all content is correctly sourced. Theroadislong (talk) 20:36, 13 May 2023 (UTC)

Equations and vectors

Proper vector notation should be used when needed, I cannot tell which $r$ should be $\mathbf {r}$ and which $r.k$ should be replaced by $\mathbf {r} \cdot \mathbf {k}$. ReyHahn (talk) 14:09, 27 April 2023 (UTC)

A good suggestion, done. Ldm1954 (talk) 20:14, 27 April 2023 (UTC)

Topic expert

User:Ldm1954 you may be a topic expert, BUT we still require references for any content that you add. Theroadislong (talk) 17:29, 13 May 2023 (UTC)

They are already there. Ldm1954 (talk) 17:35, 13 May 2023 (UTC)

You may consider it "pedantic", and tiresome, but it is absolutely required that all content is correctly sourced. Theroadislong (talk) 20:36, 13 May 2023 (UTC)

As you have yourself stated before, science is not your area. Therefore it is understandable that you do not realise that terms & content have already been sourced, often within a sentence. Your statements about lack of content sourcing are highly inappropriate. For instance, the book by Born and Wolf has extensive information on classic wave, aperture, Fresnel and Fraunhofer diffraction. Please stop making such comments, they are not constructive. Ldm1954 (talk) 20:50, 13 May 2023 (UTC)

Science is not my area but Wikipedia is, and correct sourcing is imperative per Wikipedia:5P2 which states that "all articles must strive for verifiable accuracy, citing reliable, authoritative sources." Theroadislong (talk) 20:59, 13 May 2023 (UTC)

To repeat, it was always there. Ldm1954 (talk) 21:05, 13 May 2023 (UTC)

@Theroadislong Is there some specific concerns you have? To me, this is a comprehensive article with a very large number of references and cross links. Johnjbarton (talk) 17:40, 16 May 2023 (UTC)

I was concerned that the editor was adding content and comments based on their knowledge of the topic rather than referencing the sources. Happy to be shown the error of my ways. Theroadislong (talk) 08:12, 18 May 2023 (UTC)

History Section revised

The 2022 History section had a number of major issues. Parts of it appear to have been copied verbatim from other Wikipedia pages, some major contributions were not mentioned, many of the links were inaccurate or broken.

The current version is based upon searching various sources which are quoted in the article. Whereas the 2022 version had 11 cites, the current one has 63. The current version:

• Has a more general description of electrons in vacuum, with more accurate citations.
• Puts the work of de Broglie and Schroedinger better into context, including a quote on this from de Broglie.
• Provides credit to at least some of the founders of electron optics.
• Provides more extensive cites to the issues about who invented the TEM, which is not straightforward. I have attempted to be unbiased.
• Added the critical paper by Boersch on SAED.
• Added a bit about LEED/RHEED
• Added something about how ED was viewed for many years using a quote from John Cowley,
• Added a bit about advances. I do not think this is the place for more.

N.B., There might be duplicate references. Ldm1954 (talk) 20:53, 18 February 2023 (UTC)

Just a note, the tidbit which in turn is connected to the observations of electrostatic charging by Thales of Miletus around 585 BCE. references this paper which says in its abstract "there is no basis to believe [Thales] discovered, carried out experiments on, or systematically observed electrostatic charging." I haven't read the paper; it just caught my attention as I was skimming the History section. Wanted to make sure it's as intended. Ajpolino (talk) 05:02, 28 February 2023 (UTC)

Ajpolino it's a tricky point, and I deliberately used the word connected rather than discovered. As Daniel Lacks indicates, there is no proof -- but then our records are incomplete. For certain Thales knew of Triboelectricity charging, and the source of electron is the Greek word for amber. There is a Greek stamp with him, charging and amber, and many cites with stronger connections.

Please feel free to wordsmith this is sentence, it is generally accepted color rather than being critical. Ldm1954 (talk) 09:51, 28 February 2023 (UTC)

Schrödinger's removal and other suggestions

Firstly, most moderm physics prefer to use $\hbar$ instead of the original Planck h. Is this not the case in electron diffraction? Also modern books use $2\pi /\lambda =k$ and not $1/\lambda =k$ again is this special convention?

Secondly I suggest that the picture of Schrödinger has to go, the article has too many pictures and that figure is not adding to anything, he is not even the most famous physicist related to this topic (Thompson would be better but still unnecessary). Also the Schrodinger photo is not even referenced like the rest. To not rewrite the figures names every time one figure is removed or moved down, we should use a reference template, see an example here: [[2]]. ReyHahn (talk) 22:32, 27 April 2023 (UTC)

To clarify:

• Please see notes c & d: the text uses the crystallography convention, which is standard in electron diffraction, not the physics convention. Using the physics notation is inappropriate, sorry. (Real & reciprocal lattice conventions similarly differ, also in the note.)
• With the crystallography convention it is $h$, not $\hbar$.
• Thompson has no relevance to electron diffraction, similarly Einstein, Hertz...
• All ED theory starts with the Schroedinger equation, using Bethe's approach, it is the foundation. The quote from de Broglie's thesis is meant to indicate this (without shouting), and note b points out that Davisson and Germer knew, please check the ref if needed (I did). The text also tries to indicates this without shouting. (The methods use either Bloch waves, a Green's function approach or tight-binding, similar to band structure, but this is a massive digression.)

While automatic numbering of Figures would be nice, that template would not make it easy to cross-reference images. In the text there is need to specifically refer to these for the different cases at different places in the text. For instance, the Ewald sphere results are very different for TED, RHEED & LEED. This needs to be mentioned in the geometry, but the Figures themselves belong with the relevant text.

Finally, electron diffraction (and imaging) is image oriented. An image to illustrate each and the relevant Ewald sphere is consistent with standard useage. I see no harm in the images.

Discussion is good, particularly input from outside the field. Ldm1954 (talk) 02:59, 28 April 2023 (UTC)

Thanks you for clarifying the convention with respect to hbar, it makes sense now. Regarding the template, I think it allows to call a figure several times. As for the figures themselves, I see no harm on having an illustrated article, I just would prefer it to not be over illustrated a photo of Schrödinger is not clarifying anything.--ReyHahn (talk) 12:18, 28 April 2023 (UTC)

OK. If you were unsure, then I need to explain the notation issue better. I suspect that just having a note is not enough, it needs to be more "see Note xyz" or similar. Some wordsmithing needed.

I will play with that template in my Sandbox "soon", to see if I can tweak it into something comparable to standard publication labelling. I will do that before reconsidering the image, which is admittedly not so critical. Ldm1954 (talk) 12:26, 28 April 2023 (UTC)

N.B., you don't like Brownies? A touch of humor is needed, let's not fall asleep with dryness. Ldm1954 (talk) 19:55, 28 April 2023 (UTC)

See WP:JOKE.--ReyHahn (talk) 12:08, 3 May 2023 (UTC)

Proposed less steep intro text for Electron Diffraction

Please see User:Johnjbarton/Electron_Diffraction_Sandbox

This version drops the intro text "Close to the atoms the changes are described as Fresnel diffraction; far away they are called Fraunhofer diffraction. " IMO here is too early and it's covered later. Also drops the note as the intro covers naturally now.

Overall I was going for a positioning with linking that set expectations.

Please feel free to use, edit, or ignore as you like. Johnjbarton (talk) 01:27, 17 May 2023 (UTC)

I like the concept, and will use it with (perhaps) a few changes. Within a few days, I have some paperwork to do first. Ldm1954 (talk) 11:48, 18 May 2023 (UTC)

I just tried, and failed. The problem is that "electron diffraction" is a generic term in normal usage for both diffraction patterns and dynamical scattering. In 99.99% of cases there are not "obstacles", they electrons change direction due to quantum mechanical elastic scattering. Therefore the idea that there is interference between different paths is not really correct for the general sense, only for diffraction patterns. I cannot find a way to incorporate these changes without making statements that are not right or might be inappropriate. Sorry. Ldm1954 (talk) 15:59, 6 June 2023 (UTC)

Re-reading I agree. I reworked it. Please take another look. In any case I think re-working the Electron Diffraction intro is worth effort. Johnjbarton (talk) 17:02, 6 June 2023 (UTC)

OK. I will have a other go in a day or so. Ldm1954 (talk) 17:04, 6 June 2023 (UTC)

Adding an image of quasicrystals might be more informative?

An example of the electron diffraction pattern of a quasicrystal

We could use an image of the diffraction of a quasicrystal in the "Aperiodic materials" sub-sub-section. This would really show the "aperiodicity" of the diffraction patterns of such materials. Currently, I am looking at figure 15 and I cannot understand why it is aperiodic from the first glance. However, the diffraction patter of a quasicrystal is obviously aperiodic. TheLonelyPather (talk) 00:04, 17 August 2023 (UTC)

i am OK with replacing the current Figure 15 -- it's not mine, but she won't mind. The text would need to be changed with a high-schools explanation of how it is aperiodic in a few sentences. Do you want to take a stab at it in the talk? Ldm1954 (talk) 01:36, 17 August 2023 (UTC)

All right, I will give it a try...

An extreme example of aperiodic materials is for quasicrystals. Atoms in quasicrystals are ordered, but they do not have a repeating pattern and has no translational symmetry. An example is given in Figure 15...

I am not very sure how to introduce the image through the text, and I don't know enough sources to properly introduce quasicrystals. @Ldm1954: please go for it. I trust in your expertise. TheLonelyPather (talk) 13:07, 17 August 2023 (UTC)

Thanks for the description. I could not find a description for the particular DP that is shown, so I have used one of mine which is decent, but perhaps not so good. If you can find a description (and reference) for the one on the aperiodic page I will switch. Ldm1954 (talk) 19:18, 17 August 2023 (UTC)

References

Names

Can we write the full names of scientists when first named in the article? If this was a scientific journal there will be no problem but as this is a large encyclopedia many authors with the same last name exist. Also it allows for quicker recognition (and it does not affect word count that much). ReyHahn (talk) 00:54, 10 October 2023 (UTC)

Done, although I could not find a few. I am going to post a related question on links to the Physics page. Ldm1954 (talk) 14:39, 11 October 2023 (UTC)

GA Review

The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

---

This review is transcluded from Talk:Electron diffraction/GA2. The edit link for this section can be used to add comments to the review.

Reviewer: FuzzyMagma (talk · contribs) 10:35, 27 October 2023 (UTC)

GA review – see WP:WIAGA for criteria

1. Is it well written?

   A. The prose is clear and concise, and the spelling and grammar are correct:

   B. It complies with the manual of style guidelines for lead sections, layout, words to watch, fiction, and list incorporation:

2. Is it verifiable with no original research?

   A. It contains a list of all references (sources of information), presented in accordance with the layout style guideline:

   B. Reliable sources are cited inline. All content that could reasonably be challenged, except for plot summaries and that which summarizes cited content elsewhere in the article, must be cited no later than the end of the paragraph (or line if the content is not in prose):

   C. It contains no original research:

   D. It contains no copyright violations nor plagiarism:

3. Is it broad in its coverage?

   A. It addresses the main aspects of the topic:

   B. It stays focused on the topic without going into unnecessary detail (see summary style):

4. Is it neutral?

   It represents viewpoints fairly and without editorial bias, giving due weight to each:

5. Is it stable?

   It does not change significantly from day to day because of an ongoing edit war or content dispute:

6. Is it illustrated, if possible, by images?

   A. Images are tagged with their copyright status, and valid non-free use rationales are provided for non-free content:

   B. Images are relevant to the topic, and have suitable captions:

7. Overall:

   Pass or Fail:

Comments:

I can but feel that this work is a product of love. It is really well-thought and well-written. Most of my comments is to improve the text readability. I will add below some comments for improvement as I read through the text. Sadly I cannot edit the article directly during the review process as not to become an author. You can reply directly to each comment by just pressing reply.

• Closed: The lead need to be expanded as it stands now it does not summarize the most important points covered in an article. for an article this size three or four paragraphs can be used, see MOS:LEADLENGTH FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  I disagree. There is too much to summarize, the lead hits the key points. More is not always better, and for certain the lead is not the place to introduce the more technical aspects. Ldm1954 (talk) 19:33, 8 November 2023 (UTC)

  have a look at the featured articles Electron and Speed of light, or my favourite Laplace–Runge–Lenz vector. The current lead does not summarise the article. It does not summarise the basic section, and does not mention the types and techniques at all. The lead actually does not go beyond what is mentioned in the "Description" section FuzzyMagma (talk) 19:37, 9 November 2023 (UTC)

  I strongly disagree. In fact both Speed of light and Laplace-Runge-Lenz vector violate WP:MOS and WP:EXPLAINLEAD and Electron is marginal. To quote from WP:MOS

  It should be written in a clear, accessible style with a neutral point of view.

  The expansion in WP:EXPLAINLEAD is more specific in the second pargraph:

  For these reasons, the lead should provide an understandable overview of the article. While the lead is intended to mention all key aspects of the topic in some way, accessibility can be improved by only summarizing the topic in the lead and placing the technical details in the body of the article. The lead of the article should tell a general reader the field of study of the topic, the place the topic holds in its field of study, what (if anything) the topic is good for, and what needs to be learned first in order to understand the article.

  All three of your examples IMHO are too technical for a broad audience. To expand the lead herein would, for instance, be including some of the technical terms in the Description term, which is inappropriate. For completeness, note a and Fraunhoffer and Fresnel are in there as a critical component of non-ambiguity, Ldm1954 (talk) 21:57, 9 November 2023 (UTC)

  I think we will agree to disagree. The electron article is not far from this article when it comes to technicality and the current lead problem is not a style problem. let's wait for a third opinion on this FuzzyMagma (talk) 22:00, 9 November 2023 (UTC)

• Closed: Electron diffraction is a general term for phenomena associated with changes in the direction of electron beams due to elastic interactions with atoms I understand you want to focus on the clean aspect of diffraction but "Inelastic scattering in electron diffraction makes an unavoidable contribution to high resolution TEM images. Valence-loss, thermal diffuse scattering, and phonon scattering are some of the main sources." See chapter 6 in Elastic and Inelastic Scattering in Electron Diffraction and Imaging. FuzzyMagma (talk) 11:01, 27 October 2023 (UTC)

  I know that book, I was a postdoc in ASU while ZL was doing his PhD and he used some of my codes. It is a good book, but I would recommend more Peng, Dudarev and Whelan as a source.

  While inelastic contributes, it cannot be properly included without getting into details of dynamical electron diffraction, e.g. the optical potential in HHNPW. I view that as a big digression. Writing that page is on my "To Do" list. Sorry, I prefer not to include that. Ldm1954 (talk) 19:07, 30 October 2023 (UTC)

  maybe do not include it in the lead but inelastic diffraction need to be mentioned somewhere in the article and described briefly. For the lead please include a note and mentioned why inelastic diffraction is not being considered in the article. The reader needs to know that "While inelastic contributes, it cannot be properly included without getting into details of dynamical electron diffraction, e.g. the optical potential in HHNPW." btw you already touch on the topic in the "Diffuse scattering" section. FuzzyMagma (talk) 16:42, 1 November 2023 (UTC)

  It is already mentioned in several places, for instance in Dynamical diffraction there is the optical potential, with Figure 7 and Figure 18 showing it; it is mentioned in Kikuchi lines. Please note that diffuse scattering is not necessarily inelastic, there is more than thermal diffuse. Let's leave this until you have looked at everything else please. Ldm1954 (talk) 22:54, 2 November 2023 (UTC)

• Closed: Some details on methods for sample preparation of thin samples can be found in the book by Jeffrey Williams Edington, within journal publications, in the unpublished literature and within the page transmission electron microscopy.. I do not think this relevant here and at best the Jeffrey Williams Edington work can go into further readings section in TEM article (not this article) or can be expanded into a section there but not on this article.FuzzyMagma (talk) 11:02, 27 October 2023 (UTC)

  Changed Y: Ldm1954 (talk) 17:29, 30 October 2023 (UTC)

• Closed: for Figure 2, multiple images at 400 px can fit at the right side of the article (see MOS:IMGSIZE). To do that you may want to go to the image and make the "Frame width" 400 and then change the "Alignment" to right. Also in general as per MOS:IMAGELOC, try to keep the images in one side to ovide sandwiching texts between imaging as fig 11 and 12 (see MOS:SANDWICH). FuzzyMagma (talk) 16:54, 27 October 2023 (UTC)

  I adjusted those. Figure 2 is OK, I am not enthused by the others but will leave. (I am not switching to 400).Y Ldm1954 (talk) 19:42, 8 November 2023 (UTC)

• Closed: The simplest approximation using the de Broglie wavelength for electrons, where only the geometry is considered and often Bragg's law is invoked, a far-field or Fraunhofer approach. you may want to re-phrase the sentence, it does not read-well especially the a far-field or Fraunhofer approach does not make sense.FuzzyMagma (talk) 11:02, 27 October 2023 (UTC)

  I changed both 1. and 3. to try and make them clearer.Y Ldm1954 (talk) 19:02, 30 October 2023 (UTC)

• Closed: but the higher level ones cited above and later are needed for many details and the intensities – numbers matter. the higher level of what? I assume modells or assumed complexity. What "number matters"? I am assuming the spot/pattern intensity and intensity distribution which you cannot get from geometrical nor kinematic solutions. This need to be stated clearly.FuzzyMagma (talk) 11:02, 27 October 2023 (UTC)

  I changed it to Simple models give the geometry of the intensities in a diffraction pattern, but dynamical diffraction approaches cited above and briefly describe later are needed for accurate intensities and positions of diffraction spots.Y Ldm1954 (talk) 17:37, 30 October 2023 (UTC)

• Closed: name ēlektron comes from the Greek link the work electron to Wikidictionary using like this "name ''[[wikt:electron|ēlektron]]'' comes from the Greek" FuzzyMagma (talk) 15:57, 27 October 2023 (UTC)

  Not quite. The word ēlektron is Greek so the correct link which I added is ēlektron.Y Ldm1954 (talk) 19:31, 30 October 2023 (UTC)

• Closed: called the Schrödinger equation change to "called the Schrödinger equation" with equation included in the wikilink FuzzyMagma (talk) 16:02, 27 October 2023 (UTC)

  Done Y Ldm1954 (talk) 18:34, 30 October 2023 (UTC)

• Closed: in general, do not use bold when writing "Figure 5" or any other figure as per MOS:NOBOLD. Or use <strong>...</strong> if you think it muse be used as in the caption of figures (although think you need to use it at all) FuzzyMagma (talk) 16:34, 27 October 2023 (UTC)

  I have put in a temporary cure, will do it better tomorrow Ldm1954 (talk) 05:04, 31 October 2023 (UTC)

  I have cured this with good internal links to the Figures.Y Ldm1954 (talk) 22:55, 2 November 2023 (UTC)

• Closed: Shoji Nishikawa and Seishi Kikuchi used Cathode Rays in 1928 to see Kikuchi lines (see Diffraction of Cathode Rays by Calcite. Nature 122 (1928) 726) but this is not mentioned in the history section FuzzyMagma (talk) 16:42, 27 October 2023 (UTC)

  I did some research. The paper you mention cites Proceedings of the Imperial Academy. 4 (6): 271–274, and there is also Japanese Journal of Physics. 5 (3061): 83–96 which many other sources cite. For certain the Proceedings paper has "nice" Kikuchi lines. I could not find the other paper anywhere. I have left it as those two -- the Nature paper is later. Ldm1954 (talk) 18:36, 30 October 2023 (UTC)

• Closed: in "See also" section please remove all of the pages that already mentioned in the article, like Transmission electron microscopy, as per MOS:ALSO FuzzyMagma (talk) 17:03, 27 October 2023 (UTC)

  This is one of those cases where I disagree with WP:MOS, and agree with many in the Rfc on this. I've removed the whole section, as I don't want to leave a few lame additions if I am removing the important ones.Y Ldm1954 (talk) 18:52, 30 October 2023 (UTC)

• Closed: (Sometimes reciprocal lattice vectors are written...), you do need the brackets FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  I think so, it is an aside, albeit an important one. Ldm1954 (talk) 16:37, 3 November 2023 (UTC)

  sorry I meant, you do not need. I am bit dyslexic FuzzyMagma (talk) 16:41, 3 November 2023 (UTC)

  No problem. To clarify, because it is an aside the brackets are appropriate.Y Ldm1954 (talk) 22:39, 7 November 2023 (UTC)

• Closed: sphere is called the excitation error unbold FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  DoneY Ldm1954 (talk) 16:38, 3 November 2023 (UTC)

• Closed: For both LEED and RHEED the .. make it the start of a new paragraph please FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  I added one, except it goes before the "For transmission" as the shape function is being described in all the cases.Y Ldm1954 (talk) 16:42, 3 November 2023 (UTC)

• Closed: Laue zone (HOLZ). after this sentence you have an empty line, please remove it FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  Empty lines keep cropping up for reasons I don't understand -- I keep delelting them.Y Ldm1954 (talk) 16:42, 3 November 2023 (UTC)

• Closed: (This is a three dimensional integral, which is often written ...) you do need the brackets FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  Again, it is an aside, albeit important so a bracket is appropriate. Ldm1954 (talk) 16:43, 3 November 2023 (UTC)

  Grammatically speaking, you normally don’t start a sentence and end with brackets. FuzzyMagma (talk) 18:48, 3 November 2023 (UTC)

  Sorry, I do not agree and other sources also do not. Ldm1954 (talk) 22:41, 7 November 2023 (UTC)

• Closed: In Kinematical theory an wikilink Kinematical theory to Kinematics FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  Definitely not, sorry, kinematical theory in diffraction is not close to Kinematics. Kinematical theory is not classical, it is effectively the first Born approximation. Ldm1954 (talk) 16:45, 3 November 2023 (UTC)

  I will later create a redirect that point to this section in the electron diffraction article FuzzyMagma (talk) 18:49, 3 November 2023 (UTC)

• Closed: which are called Bloch-wave approaches link to Bloch's theorem and I hope you can put Dynamical diffraction in your to do list FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  The problem is that in ED theory, the term "Bloch-wave approach" is used for matrix methods, e.g. HHPNW Chapter 9. Bloch waves are the form of the solution used, but I think this might mislead so I prefer not to.

  I do intend to do Dynamical diffraction (electron) at some stage. I added to Dynamical diffraction that most of that page is for x-rays, as the electron case is very different. Ldm1954 (talk) 16:50, 3 November 2023 (UTC)

• Closed: Contributions to the diffraction from elastic strain and defects link Elasticity (physics)# and [[Crystallographic defect] FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  Done. There may be others needed.Y Ldm1954 (talk) 16:54, 3 November 2023 (UTC)

• Closed: These occur simultaneously, and cannot be separated – the Copenhagen interpretation do you mean "i.e., the Copenhagen interpretation" or "this is known as the the Copenhagen interpretation" FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  I changed it. I have seen too many people say "the electrons are inelastically then elastically scattered", which is not right as this is unmeasurable. I am trying to correct this. Ldm1954 (talk) 17:05, 3 November 2023 (UTC)

• Closed: determine crystal orientation link to Orientation (geometry) FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  Done.Y Ldm1954 (talk) 17:07, 3 November 2023 (UTC)

• Closed: Thank you very much for donating your own images to commons. Can you please keep images to one side if you can, i.e., Figure 10, 11, 14, 18, 22, 23 per MOS:IMAGELOC and also to avoid sandwiching text between images (see MOS:SANDWICH) which is happening between Figure 11 and 12, 14 and 15, 17 and 18, 21 and 22. You can make sue of multiple images but horizontal at 400px width as you did in figure 13, for example for 17 and 18, 20 and 21, and 22 and 23 FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)
• Closed: including magnetic lenses, deflectors and apertures link also to Detectors for transmission electron microscopy FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  Sorry, but that section is about manipulating the electrons, so I think detectors does not belong here. It goes at the end of the Formation of a diffraction pattern section.Y Ldm1954 (talk) 17:11, 3 November 2023 (UTC)

  sorry I read "deflectors" as "detectors", my mistake FuzzyMagma (talk) 17:42, 3 November 2023 (UTC)

• Closed: rephrase Which part? This one can never say as electrons are everywhere until they are detected (wavefunction collapse) according to the Copenhagen interpretation. as it can be confused for using original research where it reflect the current "consensus" FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  I don't understand your point, as references 112 & 113 are on the Copenhagen interpretation. Ldm1954 (talk) 21:44, 3 November 2023 (UTC)

  You asked a question “Which part?” And answered it using Wikipedia voice. Plus, who/what is “This one”? FuzzyMagma (talk) 23:23, 3 November 2023 (UTC)

  I, reluctantly have changed it.Y Ldm1954 (talk) 22:44, 7 November 2023 (UTC)

• Closed: set of magnetic lens magnetic lens is overlinked and also later convergent beam electron diffraction, Copenhagen interpretation, crystal structure, and TEM. I understand we do not want people to search for the 1st mention with a wikilink for a specific word, but these are overlinkeded in the same section at least twice. FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  I cleaned up the magnetic lens and convergentY Ldm1954 (talk) 20:27, 8 November 2023 (UTC)

• Closed: remove Herein the focus is on collecting a diffraction pattern; for other information see the pages on TEM and scanning transmission electron microscopy. instead add main article to the at the start of the section if necessary. FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  Sorry, if I did that then it would imply that the whole section #Formation of a diffraction pattern should go to those other pages. That is not the intent. I and describing the key components of an experimental DP, and saying to go elsewhere just for the imaging. Ldm1954 (talk) 21:43, 3 November 2023 (UTC)

• Closed: so is only accurate for large grains with tens of thousands of atoms or more; for smaller regions a focused probe is needed., ost of these are the same, although there are instances such as momentum-resolved STEM where the emphasis can be very different., The diffraction intensity is a sum of several components such as background, atomic intensity or molecular intensity and Hence x-ray diffraction remains the preferred method for precise lattice parameter measurements. citations are needed for these sentences FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  For the first "so is only" the citation is already there to [[11]Chpt 5-6

  For "most of these are the same", that whole sentence sites different names for the same thing, see the Gatan page.

  I added a cite to one of Quentin's recent papers for vibrational momentum resolved STEM

  "Sum of several components" the reference was already there, I repeated it.

  I removed the sentence about x-ray being preferred, it is true but not needed.

  Y Ldm1954 (talk) 19:31, 8 November 2023 (UTC)

  please continue using in-line citation and just add it to the end of the sentence: so is only accurate for large grains with tens of thousands of atoms or more; for smaller regions a focused probe is needed.. We are almost there FuzzyMagma (talk) 20:59, 8 November 2023 (UTC)

  Done, although I think that is overciting. Ldm1954 (talk) 21:05, 8 November 2023 (UTC)

  thanks, WP:Overciting refers to citation clutter and staking references to appear legit. Your work is the very opposite. It is legit, written by a leading expert in the field]] but just need to fulfil Wikipedia style. I have no doubt about any fact written in this article but I just need to apply the criteria of GA for a vital article. Have a look to Wikipedia:Expert editors FuzzyMagma (talk) 21:13, 8 November 2023 (UTC)

• Closed: which cannot be described as a multiple of remove cannot italics FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  OK.Y Ldm1954 (talk) 21:38, 3 November 2023 (UTC)

• Closed: In the pattern there are pentagons which are a characteristic should "In the pattern there are pentagons" be linked to Pentagonal tiling or Penrose tiling? FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  Not really. While Penrose tilings and quasicrystals can have pentagons, here I am just connecting to a feature in the pattern. I will leave the details to the existing, good quasicrystals page. Ldm1954 (talk) 17:13, 3 November 2023 (UTC)

• Closed: two-dimensional projection available in SAED what is SAED? FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  Added the definition (Selected area electron diffraction)Y Ldm1954 (talk) 17:14, 3 November 2023 (UTC)

• Closed: ..., for instance a ronchigram is as an example. should be "..., for instance a ronchigram." FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  Yes, clumsy phrasing.Y Ldm1954 (talk) 17:16, 3 November 2023 (UTC)

• Closed: you can remove , see the main page for more information as the wikilink means that FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  Done, I also rewrote parts of the PED section.Y Ldm1954 (talk) 21:37, 3 November 2023 (UTC)

• Closed: The technique has applications in visual diffraction imaging, phase orientation and strain mapping, i am guessing you mean phase identification, and orientation and strain mapping. You can also wikilink Phase diagram FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  That was a legacy sentence, I rewrote it. Sorry, I view phase diagrams as somewhat different, so I prefer not to. Ldm1954 (talk) 21:24, 3 November 2023 (UTC)

  Out of interest, how is phase diagram is different? What does phase means in this sentence? FuzzyMagma (talk) 22:57, 3 November 2023 (UTC)

  A phase is a specific crystallographic structure and chemical composition or range of compositions for a solution. A phase diagram is a representation of the different phases as a function of composition and, sometimes, temperature & pressure. For instance, water, steam and ice are three phases of H2O; which is present with T/P is a phase diagram. Ldm1954 (talk) 23:07, 3 November 2023 (UTC)

• Closed: the sample , although remove the space before the comma FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  Done.Y Ldm1954 (talk) 21:24, 3 November 2023 (UTC)

• Closed: unbold excitation error FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  Done.Y Ldm1954 (talk) 21:27, 3 November 2023 (UTC)

• Closed: they can also be used for phase identification or strain analysis please wikilink "strain analysis" to HR-EBSD FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  Done.Y Ldm1954 (talk) 21:29, 3 November 2023 (UTC)

• Closed: you need to include citation for note b and c (excluding a and d to some extent) especially note b Many sources state that the Davisson-Germer work proved the de Broglie hypothesis.. FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  Not really appropriate. Three points:

  a) It is not general practice to call out errors. Therefore it would be inappropriate to put locations to the "Many sources" in Note b. The main points in Note b refer back to the main text.

  b) There is already a reference for Note c in the main text.

  b) It is not possible to embed references within notes, that does not work. Ldm1954 (talk) 23:07, 7 November 2023 (UTC)

  “Many sources” without a source is a WP:weasel wording and unacceptable use WP:Wikivoice if not used with sources. In most of this review when there is an issue of style, I tend not to pushback this is not an style problem. It’s a 2.b GA issue.

  As for c, please add the source as references need to be inline even for notes FuzzyMagma (talk) 23:46, 7 November 2023 (UTC)

  I will edit tomorrow. However, you cannot reference inline within a note, that is a Wikipedia deficiency (I checked). Ldm1954 (talk) 23:48, 7 November 2023 (UTC)

  I edited note b to remove Many sources. Note c already has them so there is no need. To repeat, I used it deliberately to refrain from calling out errors, which is polite writing style in science.Y Ldm1954 (talk) 19:44, 8 November 2023 (UTC)

• Closed: further reading, normally includes books that are not cited through the article but it is understandable to put the important text books. However, you need to be put in the appropriate template, for example

• Cowley, John Maxwell (1995). Diffraction physics. North-Holland personal library (3 ed.). Amsterdam New York: Elsevier Science B.V. ISBN 978-0-444-82218-5.

FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

Changed. Y Ldm1954 (talk) 23:25, 7 November 2023 (UTC)

• Closed: A personal request, can you please add an external links sections for videos and codes (for data analysis and simulation) that can help the reader learn more about this topic FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

  I will add. I have several from teaching, but I need to check they are still alive. Ldm1954 (talk) 21:29, 3 November 2023 (UTC)

  Not today, that can come later as it is not really part of GA.Y Ldm1954 (talk) 19:45, 8 November 2023 (UTC)

References spot checks:

• Ref 8 (Low-Energy Electron Diffraction), 9 (Reflection high-energy electron diffraction), 108 (Practical Electron Microscopy in Materials Science), 113 (Falling Felines and Fundamental Physics), 115, 116, 117, 119, 121, 125, 147, 160 and 168: These are books. You need to include the page number as you did with the other books especially when it used more than once.
• Ref 20 points to one page 183 and used 3 times only the 1st one check out
• Ref 11.k: checks out
• Ref 98: Checks out
• Ref 102: checks out

FuzzyMagma (talk) 11:58, 3 November 2023 (UTC)

First, for the books, there are two classes of references:

1) Those where a specific point is being made which connects to some specific location in the text.

2) Those where it is general, and the whole book is relevant.

8, 9, 109, 116, 117, 119, 121, 147, 160 are all, deliberately, the whole book

113 was a citing glitch as the Book and Chapter are the same, corrected

115, 125, are from a prior editor, I will adjust tomorrow

You suggested 168, so please provide some page numbers! Ldm1954 (talk) 23:42, 7 November 2023 (UTC)

Nope! I need to be able to verify the information in order for this article to pass. As for 168, am not sure what you mean by “you suggested 168”. I do not remember doing that FuzzyMagma (talk) 23:48, 7 November 2023 (UTC)

Correction, you did not recommend 168. I will edit that tomorrow.

The "whole book" citations are correct. As an example, for 8 the wording is "it is a technique called LEED ^[8]", and the reference is a book that describes LEED. If I included page numbers they would be to the whole book, which would be inappropriate. Ldm1954 (talk) 00:10, 8 November 2023 (UTC)

I will ask for a second opinion although am sure I am correct FuzzyMagma (talk) 08:09, 8 November 2023 (UTC)

Please let me finish everything else first.

If a whole book is relevant then page numbers make no sense. As I said before, the reference is to LEED which is the topic of the book; page numbers 1-622 is identical to all pages, this is the standard short form. Please remember that common sense should always be applied, it is an accepted term. Ldm1954 (talk) 09:42, 8 November 2023 (UTC)

115 and 125 have been removed, it were inappropriate references from a prior editor of a weak earlier version.

168 has been cleaned up (not 166 with page numbers)

Pages corrected with 20

References are all done.Y Ldm1954 (talk) 19:20, 8 November 2023 (UTC)

That list was not exhaustive btw although you also did not fix all of them, here in details from this version of the article you still have Ref 2, 8, 9, 59, 77, 86, 108, 113, 114, 115, 116, 117, 118, 119, 120, 133, 144, 159, and 167 FuzzyMagma (talk) 20:55, 8 November 2023 (UTC)

2,8,9,59,86, 114, 115, 118, 119, 120, 144, 159 are all books. They are correct as is.

Added for 77

113, 167 done before

There is nothing wrong with 133, it has page numbers

Delete 108, 116, 117 Ldm1954 (talk) 21:36, 8 November 2023 (UTC)

To be clear, let me give an example sentence:

"George wrote a textbook.[1]"

You don't do page numbers, the whole book is the reference. Ldm1954 (talk) 03:35, 9 November 2023 (UTC)

I really do not understand why are you saying that books are ok especially books you used more than once.

Pages needed for 2c, 8d, 9b & f, 59, 77, 86a & e, 108, 112, 113 a to d, 114, 115, 116, 117, 118, 119, 120, 133, 144, 156, and 167 FuzzyMagma (talk) 19:27, 9 November 2023 (UTC)

Sorry, for start you are incorrect about 112, it has pp 243–263 so the use of {{Rp}} is wrong.

I will give two more examples.

a) George wrote a book.[1]

b) As part of his book George describes a trip to Atlanta.[1]{{Rp}}

1. George's Book, published by ...

These are correct. In a) the source is the whole book, no pages. In b) it is necessary to include the pages which detail the trip.

You are incorrect about the references, they are all "a)" above. I won't go over all of them, just three examples with the quoted text:

"The normal usage in the field."[2] (which refers to 2c). The book is on TEM, which is the field. This is deliberate and correct; in some other locations I do use [2]{{Rp}} when b) is appropriate.

"Electron diffraction in a TEM exploits controlled electron beams using electron optics.[114]" and the book is on Electron Optics. It would be inappropriate to give page numbers.

"The main uses of RHEED to date have been during thin film growth,[156]", the title of the book is Applied RHEED : reflection high-energy electron diffraction during crystal growth. Ldm1954 (talk) 20:18, 9 November 2023 (UTC)

@Johnjbarton and @RoySmith: this one FuzzyMagma (talk) 08:49, 12 November 2023 (UTC)

I haven't been following this in detail, but the general rule is the citation needs to make it easy for the reader to verify the material. If you are citing a book, or even a chapter in a book longer than a couple of pages, you need to tell the reader exactly where to look, either by citing a specific page or short range of pages in the citation itself, or by augmenting the citation with additional location information via {{rp}} or something similar. Looking at the thread above, I'd say that "243–263" is a long enough span of pages that you really do need {{rp}} to narrow things down. RoySmith (talk) 11:48, 12 November 2023 (UTC)

Dear Roy, unfortunately that is not how science referencing works in general. Almost always articles contain background, experimental/theoretical methods and results all of which explain/justify certain conclusions. While there are a few exceptions, it is very rare to quote just a single page from a science article, it would be considered inappropriate. As one example, [16] is all about where to trace the source of elektron, detailing that it is wrong to just attribute it to Thales although many have.

With a book or book chapter, in journals the whole book/chapter is normally cited. Within Wikipedia it depends. For the book chapter [20] it is pages 83-86 because the rest is less relevant. In many cases I use the whole chapter from a book because it all has to be read, it is wrong to extract. Yes, that does mean that a reader has to read the whole chapter to verify/understand in detail. In a few cases I have included "field references", i.e. a whole topic, and these have no pages. To give an analogy, in general you would not select pages from a book if you are citing the field of Quantum Mechanics, you would cite the whole book. You can contrast this to a Chapter on the uncertainty principle, and perhaps a single page one when Schroedinger first published his equation. Ldm1954 (talk) 16:01, 12 November 2023 (UTC)

Just like the variation between different scientific journals, there is variation between how journals do things and how WP:GA does things. One might call it our house style. It would be presumptuous of me to claim that our way is better, but it is our way. And just like with journals, nobody is forcing you to follow their house style but by the same token nobody is forcing the journal to publish your paper.

In our house style, we differentiate between in-line citations and general references; this is explained in the introductory section of WP:Inline citation. It sounds like what you want to do is make the reference in question into a general reference placed in a bibliography section instead of trying to shoehorn it into the in-line citation format. RoySmith (talk) 16:24, 12 November 2023 (UTC)

I agree. The goals and audience for scientific references and for Wikipedia references are quite different. In Wikipedia references support text not being deleted. Full-book references make it too difficult for editors to verify text. Johnjbarton (talk) 16:54, 12 November 2023 (UTC)

I think the reference 2c is not useful as presented. The sentence is

• The normal usage in the field is to collectively refer to both the scattering process and the maps of directions as electron diffraction, not differentiating the two.

The item of information here that a reader or editor may wish to learn more about is not "the field" but rather that "normal usage...collectively refer". Three references to books about "the field" are not helpful. One reference to a specific page would work, but as this is really more of an issue of "common knowledge" I think such a page may not be easily found. An alternative could be two references, one on scattering and one on maps-of-directions, each using the term "electron diffraction".

For the case

• "Electron diffraction in a TEM exploits controlled electron beams using electron optics.[114]" and the book is on Electron Optics.

The item of information is "TEM, controlled beams" and the reference should be to a description of controlled beams for TEM. The words 'electron optics' could be wikilinked, but a text on electron optics is not useful for the item of information.

For the case

• "The main uses of RHEED to date have been during thin film growth,[156]", the title of the book is Applied RHEED

Similarly the item of information is "main uses". The reference is specific to crystal growth. If the text actually says that it covers the main uses of RHEED, that page should be cited. Otherwise the current full book citation would be ok if the text instead said something like "RHEED has been applied to study thin film crystal growth", shifting the item of information to the topic of the book. Johnjbarton (talk) 16:26, 12 November 2023 (UTC)

placed the article on-hold for 2 weeks to allow for the reference problem to be fixed. ping me when you are done FuzzyMagma (talk) 18:46, 20 November 2023 (UTC)

I am done. Relevant page/Chapters are all included. Ldm1954 (talk) 18:49, 20 November 2023 (UTC)

then congrats. Thanks for your patience and the effort that you put to improve this article and Wikipedia coverage. Good luck and sorry if you felt that my comments were too much FuzzyMagma (talk) 18:51, 20 November 2023 (UTC)

Some drive-by comments by RoySmith

I've been asked to comment on a couple of specific issues in this review. Use these comments however you see fit. RoySmith (talk) 17:46, 10 November 2023 (UTC)

Regarding the lead, I agree it could include more material. In general, I think people tend to cram too much detail into leads, so I'm sympathetic to the view that "More is not always better". I don't think we need to be a slave to the numbers suggested by MOS:LEADLENGTH, but in this case, the lead is substantially shorter than suggested, so it's worth considering augmenting it.

To get a trivial point out the way quickly, the lead mentions studying the atomic structure of liquids, which as far as I can tell isn't talked about in the article.

I'm sensitive to the "Make the lead section accessible to as broad an audience as possible" requirement of MOS:INTRO so I agree that the more technical material in the article is not appropriate for the lead. It's hard to know what exactly constitutes a "broad audience". For a technical subject like this, I think it's fair to assume general knowlege about the subject. I'm not a physicist, but I did well in my physics courses in college (a long time ago) and I have kept up an interest in the subject. I'm currently working my way through the MIT Open Courseware videos on intro to quantum mechanics. So I think I'm a reasonable approximation to the intended definition of appropriately broad audience. With that out of the way, here's a bullet list of things I see in the article which could usefully be covered in the lead:

• How the early work on CRTs led to an understanding of particle nature of the electron and an estimate of their mass.
• How experiments in the early 20th century (Davisson–Germer, etc) led to the realization that the particle nature was an incomplete understanding.
• How increasing understanding of electron diffraction led to advances in electron microscopy.
• "Often combined with other methods"
• "sometimes to solve an unknown crystal structure."
• " TEM analysis ... can be used to obtain information from ... just a few or even single atoms."
• Can be used to analyze quasi-crystals and aperiodic crystals.

This is not an exhaustive list, just some items I noted by reading through the article quickly. I think the bottom line is that there's certainly more topics which are mentioned in the article which could be mentioned in the lead without digging into excessively technical details. RoySmith (talk) 17:46, 10 November 2023 (UTC)

Thanks. I will add a little non-technical to the lead, and I agree with you it needs to be non-technical; I accept that JohnJBarton also suggests expanding the lead slightly, again non-technical. I will have to think, carefully how to do this cleanly. (There was a disagreement with FuzzyMagma on how technical it should be as you probably noted.)

N.B., there is nothing special about electron diffraction of liquids, they are put into a cell. It is just not that common, so not expanded upon. I will ponder deleting it as a digression that could confuse. Ldm1954 (talk) 03:54, 11 November 2023 (UTC)

If it's interesting enough to be called out in the lead, then it's interesting enough to be covered in the article body. And vice-versa. RoySmith (talk) 14:55, 11 November 2023 (UTC)

@RoySmith since you are here, can you please advise on the reference. The point just above your comment FuzzyMagma (talk) 18:32, 11 November 2023 (UTC)

Requested review

@FuzzyMagma asked me to review this article, I believe in an overall sense rather than in detail.

Broadly the article is fantastic with lots of interesting subtopics, images throughout, and an excellent coverage of relevant, mostly secondary references. My comments are only intended to help further improvement and not to detract from what I think should be a GA pass.

I agree with @FuzzyMagma that the introduction section does not represent the article. The outline of the article is clean and clear: History, Physics (called basics), Types and Techniques. But the intro is dominated by physics and some of that discussion does not even seem to be in the article. The article is strong on applications and has a solid history section. I think the lead should give a sense of the era (one sentence with dates for discovery and a couple of key technology introductions) and outline techniques/applications. To be specific, I would move the second paragraph into the body and replace it with the fourth paragraph of the Description (the paragraph with TEM, SEM, RHEED, LEED, etc).

I found the first sentence puzzling: it reads like a description of reflection or at most scattering. It certainly makes electron diffraction sound like a particle effect. This contrary to both the History and Description sections.

The Description section is essential a continuation of the introduction. So the introduction is too short but the combination is too long. Some of the Description material could go into the introduction paragraphs for the major outline sections. Again to be specific I would shoot for four paragraphs of introduction: lede, physics, history, and techniques, each a summary, not new material. Then I would disperse the remaining Description to the heads of sections.

To me the section "Basics" is "Physics". It's not a section on basic techniques for example, just about physics. Similarly the section "Types and Techniques" would be clearer and more interesting as "Techniques and Applications".

The "Electrons in a vacuum" is relevant to the applications section but not obviously essential for "electron diffraction". I suggest calling out the connection in the first sentence of the section. eg "The discovery of electron diffraction built upon a long history of scientific inquiry into "electricity" and "cathode rays" culminating in the discovery of the electron."

The sentence in the de Broglie section "He proposed that particles are bundles of waves (wave packets) that move with a group velocity and have an effective mass, see for instance Figure 4." needs a reference. As I read de Broglie's thesis he is very careful not to say anything beyond the wave being "associated". His derivation is based upon special relativity so he knows the meaning of wave packets is unclear. Heisenberg famously shows that Schrodinger's equation does not allow general interpretation as wave packets. The interference phenomenon of diffraction cannot be explained by wave packet on the size of electrons, so I don't understand why this sentence is even included.

The section heading "Further developments in methods and modelling" understates the impact of the work discussed. Maybe "Quantitative analysis"?

The section on "Geometrical considerations" is rather long and does not come across as geometry at the outset. I think this section would be much stronger if it started with a diffraction pattern and geometrical analysis, then plane waves. That would lead to discussing energy/wavelength issues in a separate subsection.

From here on the article enters very strong sections.

The article does not cover some kinds of electron diffraction, eg photon-induced electron diffraction. I think it would benefit from a bit more comparison to x-ray and neutron. These can be mentioned in future edits.

Hope this helps. Definitely a GA article IMO. Johnjbarton (talk) 16:51, 10 November 2023 (UTC)

A lot of good points John. Just a couple of quick responses, I will look more but I have a couple of papers to finish:

• There is masses which is not covered, for instance Dynamical electron diffraction, Ultrafast electron diffraction, Photoelectron diffraction, Point source electron diffraction, Critical voltage effect, Borrmann effect (for electrons) etc and this list is not complete -- note the red. I tried to draw the line at those with thousands of papers.
• I will cross-check de Broglie's thesis, but when I read it some months ago that idea was there, and I believed his thesis is already referenced. He did not talk about travelling wavepackets, rather as electrons around atoms as wavepackets. Of course this was before the formal math.
• As I am sure John knows, there are stacks of papers/sites which claim that ED proved the de Broglie hypothesis, despite the fact that the papers say it did not as mentioned in the article. This kindoff wave matters.
• The electrons in vacuum history part is background to microscopes, so IMHO it belongs.
• The Further developments is both theory and experiment. I agree that it is an understatement, but that is somewhat the Wikipedia way.
• Depending upon one's background, the Basics could be called Electron crystallography, Materials Science or Physics. (In the US TEM/TED is much more Materials Science than Physics.) Perhaps be neutral?
• I will think about Geometry, although that is the standard terminology when talking about Ewald sphere and projection of the Reciprocal lattice. The approach I used is the same as in Cowley and most other texts.
• The description section is supposed to be a gentle introduction to some key concepts for a high-school student.
• John, in terms of direction please remember that in vacuum the wave-vector and group velocity are in the same direction. The first sentence is kinematical (plane wave), and ignores currrent flow which is way too specialized for the lead (and this article), and only matters with things like the Borrmann effect (for electrons).
• I will look at a minor addition to the lead later, probably next week, but it has to be non-technical IMHO. I may have missed some of your points.

Ldm1954 (talk) 17:45, 10 November 2023 (UTC)

Since you have asked for the GA review, I encourage you to graciously accept more suggestions. For example, every reviewer has complained about the introduction. We are not asking for more technical content in the introduction. On the contrary I think the current introduction has too much detail. We are asking for the introduction to be an overall summary of the article, a more balanced overview. Johnjbarton (talk) 02:36, 11 November 2023 (UTC)

I will add a little so long as it is non technical, but it will take a week or so. Ldm1954 (talk) 03:43, 11 November 2023 (UTC)

Would you mind also having a look to reference issues outlined in the last comment of my review. FuzzyMagma (talk) 18:35, 11 November 2023 (UTC)

@Johnjbarton forgot to tag you FuzzyMagma (talk) 18:35, 11 November 2023 (UTC)

Sorry I'm unsure what you mean by "the last comment of my review". Can you edit in a pointer? Johnjbarton (talk) 02:27, 12 November 2023 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Lead sentence.

A suggestion for the first sentence:

Electron diffraction refers to the change in the direction of electron beams passing near atoms and the use of that phenomenon to study materials at an atomic level.

IMO the first sentence should not have a footnote. Details belong in the article. Johnjbarton (talk) 02:28, 11 November 2023 (UTC)

Image captions

Ldm1954 regarding your figures that have multiple images, could you rework the captions to be less layout dependent? For example, Figure 2 says "The first is the Young's slit experiment..." Depending on how the article is being presented, it may not be clear which one is the first. Likewise with Figures 9, 10, 13 referring to left and right. And Figure 3 (3A?) with top and bottom. This is all related to MOS:ACCIM. RoySmith (talk) 17:50, 17 September 2023 (UTC)

I have edited the captions so if they somehow get reordered which one is referred to should be clear. For instance instead of "The first..." in Figure 2 I have removed "The first" and mentioned the color of the wave and slits.

N.B., since they are composite images, at least on my computer, android phone and tablet they remain grouped together -- they are just shrunk. Ldm1954 (talk) 18:31, 17 September 2023 (UTC)

GA Review

The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

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This review is transcluded from Talk:Electron diffraction/GA1. The edit link for this section can be used to add comments to the review.

Reviewer: Phlsph7 (talk · contribs) 14:01, 26 September 2023 (UTC)

This is unfortunately a quickfail (see WP:QF): the article has many unreferenced passages and several full paragraphs lack references. This issue can be addressed by making sure that all claims in the body of the article are supported by inline citations no later than the end of the paragraph, see GA criterion 2b.

A few other observations:

• WP:EARWIG shows no copyright problems
• the article has many helpful images to visualize the topic
• some passages use Oxford commas but others don't. Consistency would be better.
• the article seems to oscillate between American English (behavior) and British English (modelled)
• Electron diffraction refers to changes in the direction of electron beams due to interactions with atoms. avoid phrases like "refers to" for the first sentence, see MOS:REFERS.
• Is the distinction between Fresnel diffraction and Fraunhofer diffraction required in the lead? Maybe the lead could be simplified by removing it to reduce the number of technical terms.
• nucleus could be thought of as standing waves, and that electrons there is a linebreak between "as" and "standing waves"
• In 1650, Otto von Guericke invented the vacuum pump allowing for study of the effects of high voltage electricity add "the" before "study" and replace "high voltage" with "high-voltage"
• He proposed that particles are bundles of waves (wave packets) which move with a group velocity replace "which" with "that"
• Others were focusing of the electrons by an axial magnetic field by Emil Wiechert in 1899, should this be "the focusing"?
• similar to a optical microscope but with magnetic replace "a" with "an"
• However, the vacuum systems available at that time was not good enough replace "was" with "were"
• This has changed, in transmission, reflection and at for low energies. should this be "at low energies"?
• The development of advanced detectors for transmission electron microscopy such as charge-coupled device or direct electron detectors, improving the accuracy and reliability of intensity measurements. replace "improving" with "improves" and maybe add a comma before "such as" to make it easier to parse.
• The set of diffractions spots at right angles this should probably be "diffraction spots"

Phlsph7 (talk) 14:01, 26 September 2023 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Response: I confess that I think that in some cases you counted references/paragraph without looking at the context. For instance, the lead paragraph for a section IMHO does not need to have references if they are given below. Also, in many cases formulae etc follow from a prior reference, which is the standard method in science -- you do not always put references at the end. In any case, I have gone over it adding a few more references, in some cases they are just duplicates. Please look at the context as well, although I realize this is technical (it has to be somewhat). In terms of the specifics you mentioned I have accepted most but some are not really correct, below with my responses in italics:

• some passages use Oxford commas but others don't. Consistency would be better.

This is because of multiple authors in the past. I checked in MS word and it had no problems with anything. I, personally, always use Oxford commas when there is a possible ambiguity, but not otherwise. No changes, sorry

• the article seems to oscillate between American English (behavior) and British English (modelled)

Again because of multiple authors and MS word had no issues. No changes, sorry.

• Electron diffraction refers to changes in the direction of electron beams due to interactions with atoms. avoid phrases like "refers to" for the first sentence, see MOS:REFERS.

I have changed the first sentence to "Electron diffraction is a general term for phenomena associated with changes in the direction of electron beams due to elastic interactions with atoms". It is a bit long, but it is accurate which is not so easy.

• Is the distinction between Fresnel diffraction and Fraunhofer diffraction required in the lead? Maybe the lead could be simplified by removing it to reduce the number of technical terms.

Sorry, this really matters. The lead here not only must describe what the article is about, but clearly define several things that it is not about. There have been questions raised about this, and some other technical issues which is why the terms are there and also note a. No changes made.

• nucleus could be thought of as standing waves, and that electrons there is a linebreak between "as" and "standing waves”

Not sure how this got there, removed

• In 1650, Otto von Guericke invented the vacuum pump allowing for study of the effects of high voltage electricity add "the" before "study" and replace "high voltage" with "high-voltage"

Yes to “the” before “study”, no to high-voltage as it is not a compound term as an adjective. Please check it, you will find that “high voltage electricity” is the standard usage.

• He proposed that particles are bundles of waves (wave packets) which move with a group velocity replace "which" with "that"

I have changed it, although I think it is wrong as the rest of the sentence is not essential

• Others were focusing of the electrons by an axial magnetic field by Emil Wiechert in 1899, should this be "the focusing"?

Sorry, “the focusing” is wrong, as focusing is a verb not a noun

• similar to a optical microscope but with magnetic replace "a" with "an"

Thanks, changed

• However, the vacuum systems available at that time was not good enough replace "was" with "were"

Thanks, changed

• This has changed, in transmission, reflection and at for low energies. should this be "at low energies"?

Thanks, changed to “for low energies”

• The development of advanced detectors for transmission electron microscopy such as charge-coupled device or direct electron detectors, improving the accuracy and reliability of intensity measurements. replace "improving" with "improves" and maybe add a comma before "such as" to make it easier to parse.

Not really correct, I changed the sentence in a different way

• The set of diffractions spots at right angles this should probably be "diffraction spots"

Thanks, changed

Ldm1954 (talk) 23:56, 26 September 2023 (UTC)

Thanks for your timely response to the suggestions and for taking the steps to implement them. I'm not sure which passages you think that I think were unsourced but I apologize if I was not explicit enough about which claims lacked references. The references you added in response already cover the most severe cases so I'll respond to some of the remaining points. Unreferenced claims in the lead are fine as long as they just summarize sourced material in the body of the article, see WP:LEADCITE. The criticism referred to the body of the article.

If a formula follows from a reference given in an earlier paragraph, it is probably best to repeat the reference. Otherwise, it would be a lot of work to verify since a reviewer would have to go through all the previous references to see whether one of them supports the formula. An exception might be if the formula itself was already explicitly stated in that earlier paragraph. It's quite possible that the Wikipedia GA criteria are different in this respect from how this is handled in other fields.

If a group of references covers all of the claims in a passage, it's usually best to put them at the end of the passage. For example, references 1, 2, and 3 in the passage The normal usage in the field[1][2][3] is to collectively refer to both the scattering process and the maps of directions as electron diffraction, not differentiating the two. Therefore, strictly, electron diffraction also plays a major role in how images are formed in different types of electron microscope such as transmission, scanning transmission, scanning and low-energy. should be put at the end if they cover all the claims. If they do not cover all of them then separate sources should be added after the passage. Otherwise, it can be difficult for readers and reviewers to assess verifiability since they would need to guess which reference might cover which sentence.

One more point regarding citations: in some cases, you cite full books without specifying a page number (e.g. "Edington, Jeffrey William (1977). Practical electron microscopy in materials science" and "M. A. Van Hove; W. H. Weinberg; C. M. Chan (1986). Low-Energy Electron Diffraction"). This makes it very difficult for reviewers to find out whether a reference verifies a claim.

In response to some of the other issues:

• in relation to American vs British English: this is covered by MOS:CONSISTENT. MOS:CONSISTENT is not included in the GA criteria so, strictly speaking, this is not required for GA status.
• in relation to MOS:REFERS: the main point is that "the article is about the subject, not a term for the subject". One way to solve this would be to use a phrase like: "Electron diffraction is a phenomenon associated with ..."
• in relation to Others were focusing of the electrons...: if I understand the sentence correctly, "Others" refers to significant steps in relation to the previous sentences (One significant step...) and means "Other significant steps". On that reading, understanding "focusing" as a verb (i.e. other significant steps were focusing of the electrons) does not make much sense to my ears and does not fit with the preposition "of". But maybe I am parsing the sentence wrong.

Phlsph7 (talk) 07:34, 27 September 2023 (UTC)

Clarifying, with numbers for your paragraphs:

2) The only formula that does not (now) have a specific reference is the one after "The wavelength of the electrons". That is just substitution of variables, so does not need a reference. Of course I am not writing a textbook here, as that would not be appropriate.

3) Sorry, but you have misread that paragraph. The references [1-3] go with "normal usage in the field". Note that both [1] and [2] do not have page numbers which is deliberate. Both books are on "the field", hence page numbers would be inappropriate. The "therefore" directly refers back to a consequence of the "normal usage". Putting the references at the end would not be so rigorous IMHO. Yes, it may be harder to validate but the reader who wants to know more has a source to read. (This is why both of these are also in the "Further reading" as well -- deliberate and accepted practice.) What I am doing in this paragraph is trying to provide complete context for the non-expert, which is not so easy in a topic as vast of this one.

4) Please look at the context. The text by Edington is a general reference for experimental details (that you can't find elsewhere), so (similar to 3) above) is deliberately the whole book. Similar Van Hove's book on LEED and Ichimiya's on RHEED are general references to areas where there are many thousands of papers. Note that for both LEED and RHEED I point towards the existing "Main articles" (also for Kikuchi, PED, CBED, 4D STEM, GED, EBSD). All these topic need to be at least mentioned, but since decent, longer articles already exist I use these for expansion.

N.B., concerning the "Others were focusing" sentence, let me give you two uses to clarify.

"The focusing of electrons can occur because they are matter waves"

"A magnetic lens can focus electrons"

In the first "focusing" is a noun equivalent, while in the second focus is a verb. I meant to use a verb. To clarify I have changed the sentence to read "focusing of electrons by an axial magnetic field". (The "of" is needed to differentiate it from, for instance, focusing of light.)

It may well be that there are areas in the article which are not so clear, and could be improved. What I am pretty certain of is that everything in it is either backed up by citations, or if I have missed 0.5% then I have them readily available, so can easily add.

Ldm1954 (talk) 18:21, 27 September 2023 (UTC)

N.B., I resubmitted the GA a few days ago. Ldm1954 (talk) 22:29, 28 September 2023 (UTC)