Talk:X-ray crystallography

Kudos to site editors, and Comment on one section

Bravi, all contributing editors here, a very nicely done article! I rarely am so impressed by our science articles; this one is very well done. Thank you all.

I would like to suggest, only, that the section "Early organic and small biological molecules" have two small matters receive attention. First, the string of references for fatty acid structures needs to be checked, and even if all fully relevant, the list of citations here seems a bit more than necessary (relative to other target molecules). Can a secondary (review) source not be found to replace, that cites this list (given the relevant WPs encouraging secondary over primary sources)? Perhaps winnowing it to the review, and the first, best, or most pedagogically helpful citation as a second ref. is the way to go.

Second, can we find a couple newer citations, to describe, to cap off the section? The pre-eminence of structural chemistry in advancing organometallic chemistry suggests adding one further sentence and review citation on structural chemistry in OM, maybe with a molecule name and picture. There, look at Arny Rheingold (http://www-chem.ucsd.edu/faculty/profiles/rheingold_arnold_l.html), who was for many years a go-to guy to get inorganic and OM structures performed, which will bring you into that literature. Maybe an Accounts article on one family of OM compounds, like carbenes (leading readers to metathesis, etc.), where structure was key to reactivity? Or perhaps chiral Lewis acid complexes important in synthesis? Then, for a second, what most momentous/small molecule structure has been solved of late? Perhaps a complex natural product whose structure was clarified/corrected by X-ray? Something to bring this close to, if not to, the new millennium.

Best wishes. These suggestions are only to make a small part more current. By the way, not a crystallographer or OM chemist, an organic/medicinal chemist that uses structure data Cheers. Leprof 7272 (talk) 00:21, 9 December 2013 (UTC)

Hi @Leprof 7272, cross-read your comment. Why not doing it...? Comment was from 2013, did you review the article in mean-time? Article looks impressive, so? KR 17387349L8764 (talk) 20:21, 12 April 2021 (UTC)

Assessment comment

The comment(s) below were originally left at Talk:X-ray crystallography/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.

The single crystal diffraction section needs a discussion of inorganic materials (e.g. that XRD is used extensively in silicon and compound semiconductor work).

Last edited at 22:49, 16 October 2006 (UTC). Substituted at 10:57, 30 April 2016 (UTC)

Laue oscillations

Hi folks, it would be great if some content could be added on Laue oscillations in this article. I am a student pursuing a Master's in Materials Physics, and when I was studying XRD and XRR, I noticed that Laue oscillations quite commonly manifest in data when performing XRD experiments, however there is no content about it in this article. What do yall think? - Blue.painting (talk) 18:07, 5 January 2019 (UTC)

Hi @Blue.painting, Ok, I Wikipedian think, why not go ahead and add it if missing? Your comment is from 2019, did you graduate in meantime? Just find some articles across Elsevier etc. and references it, no objections but think what exactly you want to say in an encyclopedic way for a general audience. I studied sciences. What you "noticed" is different from a scientific fact, please consider it. KR 17387349L8764 (talk) 20:25, 12 April 2021 (UTC)

Increased computational ability

There is no discussion of anything somewhat recent. Like every science, increased computational ability has allowed for techniques that could't be used earlier. I am pretty sure that is true here, too. Gah4 (talk) 18:02, 2 April 2019 (UTC)

Hi @Gah4, how recent please? There are citations from 2019 sources... and there is X-ray crystallography#Applied computational data analysis; What specifically do you want to read or say or ask or answer? Could you research it, insert it if available. "increasing computational ability" is a thing since 1980 tbh. All machines become "better" in that sense, including the processing, analysis power, etc. So, which techniques couldn't be used earlier, "artificial intelligence" (dude,...), but go ahead if you have any papers and cite/reference them if it is meaningful in encyclopedic-level, not "we try-out research AI"-level? KR 17387349L8764 (talk) 20:30, 12 April 2021 (UTC)

I suspect that there was a reason to write two years ago, but now I don't remember what it was. Gah4 (talk) 09:18, 13 April 2021 (UTC)

Kudos!

Kudos, everyone editing this article! Am a scientific person. I didn't review it (just surfing), but first glance says "I can see it [quality]". 17387349L8764 (talk) 20:19, 12 April 2021 (UTC)

History and kinematical diffraction

Sorry for mentioning here two quite unrelated points. First the section "X-ray diffraction". This section could probably use a bit more references, where the best one is probably the book "50 years of X-ray diffraction" by Ewald, which is freely available and already listed under "Further reading". Specifically, you will find that the historicity of the conversation in the English Garden in Munich, which is presented as fact here, is not so certain. Further, von Laue was nobilized (received the "von" to his name) only in 1913, just in time for being Nobelized in 1914 -- he did his most important work as a commoner, and specifically the author list of Ref. 22 is incorrect (he wasn't "von" then). Friedrich and Knipping were not technicians, but experimental physicists, the former a post-doc in 1912, the latter a PhD student.

The second, unrelated, point: shouldn't there be somewhere be made a point that essentially all of this article is in the framework of kinematical diffraction? Seattle Jörg (talk) 12:25, 7 April 2022 (UTC)

It seems that Wikipedia doesn't have a good description of kinematic vs. dynamic diffraction. One (non-WP) reference explains that kinematic is the reflect once approximation. If the strength of reflection off any plane is small enough, as I believe it is for X-rays, then the second order (double reflection) will be much smaller. Enough smaller to ignore. Also, at X-ray frequencies the index of refraction is close enough to 1.00 to not need consideration. Gah4 (talk) 23:05, 7 April 2022 (UTC)

That's exactly what I found at this point, therefore I started the article on Kinematical diffraction. It could already serve as a link target here, but of course it is still far from being a satisfactory encyclopedic description. I do not have the opportunity to do this now, but if you have, I obviously would be happy if you invested time there. Or is there some topical list (in this case solid-state physics would be appropriate) where articles needing fleshing out can be entered, so that motivated editors can find them? Seattle Jörg (talk) 08:11, 8 April 2022 (UTC)

General chemistry 1

Well summary not about x-ray utilizations in state of matter web and cubic crystalline structure 41.79.122.226 (talk) 12:44, 21 August 2022 (UTC)

GA Reassessment

X-ray crystallography

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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Article (edit | visual edit | history) · Article talk (edit | history) · Watch • Watch article reassessment page • Most recent review

Result: Per the discussion at WT:GAR#Please keep topical limits in mind and below, this chemistry article is far below the GA criteria. ~~ AirshipJungleman29 (talk) 18:24, 15 February 2023 (UTC)

GA from 2008. There's some uncited information including

• Finally, X-ray crystallography had a pioneering role in the development of supramolecular chemistry, particularly in clarifying the structures of the crown ethers and the principles of host–guest chemistry. X-ray diffraction is a very powerful tool in catalyst development. Ex-situ measurements are carried out routinely for checking the crystal structure of materials or to unravel new structures. In-situ experiments give comprehensive understanding about the structural stability of catalysts under reaction conditions. In material sciences, many complicated inorganic and organometallic systems have been analyzed using single-crystal methods, such as fullerenes, metalloporphyrins, and other complicated compounds. Single-crystal diffraction is also used in the pharmaceutical industry, due to recent problems with polymorphs. The major factors affecting the quality of single-crystal structures are the crystal's size and regularity; recrystallization is a commonly used technique to improve these factors in small-molecule crystals. The Cambridge Structural Database contains over 1,000,000 structures as of June 2019; over 99% of these structures were determined by X-ray diffraction.
• which is on the scale of covalent chemical bonds and the radius of a single atom. Longer-wavelength photons (such as ultraviolet radiation) would not have sufficient resolution to determine the atomic positions. At the other extreme, shorter-wavelength photons such as gamma rays are difficult to produce in large numbers, difficult to focus, and interact too strongly with matter, producing particle-antiparticle pairs. Therefore, X-rays are the "sweetspot" for wavelength when determining atomic-resolution structures from the scattering of electromagnetic radiation.
• The Electron and Neutron diffraction section.
• Each spot is called a reflection, since it corresponds to the reflection of the X-rays from one set of evenly spaced planes within the crystal. For single crystals of sufficient purity and regularity, X-ray diffraction data can determine the mean chemical bond lengths and angles to within a few thousandths of an angstrom and to within a few tenths of a degree, respectively. The atoms in a crystal are not static, but oscillate about their mean positions, usually by less than a few tenths of an angstrom. X-ray crystallography allows measuring the size of these oscillations.

And many more. Onegreatjoke (talk) 21:30, 7 February 2023 (UTC)

Saw the post at WT:MOLBIO. Woof, this article is a beast. Just in the History section this article needs some heavy lifting:

1. Too much detail/Not enough detail - some of this is undue and should be merged into the History section of X-ray or trimmed. Some is not about History and should be moved to the Theory section (e.g. the top of the "X-ray diffraction" subsection). Partly it's to make the section more readable, but also we need to make space to discuss the post-1920 history of crystallography in greater detail. This history section would make you think we stopped using X-ray crystallography 100 years ago. See this (very long) review to fill in some of the gaps.
2. Wrong citations - The History section is written like a scientific review article. The references are links to scientific works of the distant past, rather than actually supporting the claim that so-and-such discovered this-and-that.

I haven't made it further yet. But unless someone else is interested in working on this, I'm afraid it'll be a task beyond the time I have available. Ajpolino (talk) 23:11, 7 February 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.

Too long

This article would benefit from following summary style, including automatic excerpting of secondary articles via template:excerpt. fgnievinski (talk) 04:54, 9 February 2023 (UTC)

Too long, too chaotic

I think the GA reassessment was generous:

• It is way too long.

• The order of sections needs revision. For instance put all the scattering theory parts together, currently there is duplication.
• Put all relevant history parts together
• Remove unverified parts which are not central. For instance there is a paragraph on catalysts without citations. While xrd is used, it is not so key.
• Masses of citations needed. Remember, every statement needs validation.
• There is a lot of loose language which should be tightened.

It seems that people have tacked things on without enough attention to the larger picture. Ldm1954 (talk) 15:49, 10 September 2023 (UTC)

Technical Limit

I removed a paragraph that cited an error made 32 years ago, due to technical limits in the software and hardware, which no longer exist. These limits were overcome before Wikipedia was initiated. No where else does this article cite papers that were wrong due to limits in the technology at the time the work was done. Nick Beeson (talk) 20:07, 25 October 2023 (UTC)

While obviously science is self-correcting (we hope) and we don't use our own editorial interest to highlight old mistakes, this specific mistake has itself been covered as a highlight of what happened and why. Therefore I think it is quite WP:DUE to mention it. See for example doi:10.1002/anie.200460864. DMacks (talk) 03:17, 26 October 2023 (UTC)

For clarity, we're talking about Special:Diff/1181882695 (and the later Special:Diff/1188605822) here. I am not quite able do anything useful right now, but I do feel like talking about some problems is useful. I don't immediately recall anything recent about small-ish molecules like in the 32-year-old case, but it does remind me of a previously-unknown post-translation modification being missed despite visible density (doi:10.1038/s41589-021-00966-5).

...whether a mention like this is good for GA assessment purposes (length) is beyond the current capabilities of my head. Artoria2e5 🌉 11:22, 15 December 2023 (UTC)

For a GA reassment what is needed first is references (sources), as way too much has none. Can you help? Ldm1954 (talk) 17:16, 15 December 2023 (UTC)

Reorganization?

I am going to try some reorganizing next week. Phase one will be to move the 1916-20 section up to the history, and merge the duplicates of xrd discovery. The scattering sections need merging (next plausible target) so they are one, coherent section. Ldm1954 (talk) 16:37, 25 November 2023 (UTC)

Just some suggestions you probably already considered:

• Top level seems out of order:
  • History, Contributions, Sources, Methods, Analysis, or
  • History, Sources, Methods, Analysis, Contributions.
• Resection:
  • Analysis: Data analysis, diffraction theory, scattering.
  • History: plus Nobels
• Debulking, these should be short summaries with Main links
  • Electron and Neutron
  • Other Xray techniques
  • Crystallization
• Missing: some simple description of an X-Ray source.

Good luck! Johnjbarton (talk) 16:05, 26 November 2023 (UTC)

I tend to prefer history first, as such a section will outline the state of the science prior to and leading up to the current technology. BD2412 T 14:14, 30 November 2023 (UTC)

I agree, which is why I left it that way. Switching order later is trivial. Critical IMHO, references are needed, even the history has unverified statements. Ldm1954 (talk) 14:20, 30 November 2023 (UTC)

To DMacks, Nick Beeson, Artoria2e5, BD2412, Cirosantilli2, Dekonradifier, Kdliss, Michael7604

Since you have all done some recent edits I thought I would ping you with a request. I have gone over this page doing some (badly needed) reorganization, as there were many pieces which had just been tacked on. Some of these were also not really that critical. I think it is in decent starting shape, but it still has massive issues to recover close to WP:GA status. The most obvious is major sections without references. Biological crystallography is not my area, so can I request that some of you add. Please also do some condensing of those sections as appropriate. (Some sections might be better elsewhere, please add info on this to the talk page.)

I want to get it into better shape before pinging people in IUCr for some additional edits. Ldm1954 (talk) 13:39, 30 November 2023 (UTC)

Wow, that's awesome. If more university professors were into open knowledge like that, university would be in a much better place! Cirosantilli2 (talk) 15:30, 30 November 2023 (UTC)

X-ray crystallography is based on Thomson scattering.

The last sentence of Thomson scattering links this page with an unreferenced claim: "X-ray crystallography is based on Thomson scattering.". Maybe someone here has a reference handy that could be added? Even better would be another sentence explaining why. Johnjbarton (talk) 18:06, 30 November 2023 (UTC)

Section on Women in x-ray crystallography moved from Crystallography

The section on #Contributions of women to x-ray crystallography came originally from Crystallography. It seems more appropriate here, although parts (e.g. international tables) could be in both. Ldm1954 (talk) 19:27, 6 December 2023 (UTC)

Split x-ray diffraction and crystallography

The two are not the same, and there are many areas of XRD where the focus is not on detailed determination of atomic positions. Examples are powder diffraction where comparison is made to known samples, SAXS and many more. There are many areas/pages where it is relevant to say "use XRD" but wrong to say use "X-ray crystallography". I am posting here for comment before doing it. Ldm1954 (talk) 07:35, 14 April 2024 (UTC)

Thanks for posting the question. It might be better then to change the name of the article to X-Ray Diffraction, and then X-ray crystallography becomes a major heading within it. It's just misnamed. Martino3 (talk) 04:24, 18 April 2024 (UTC)

The current article has stacks on structure determination, which is I argue is "X-ray crystallography" so should stay there. Then XRD can be cleaner Bragg/Kinematical with a bit on dynamical, SXRD and perhaps small angle and soft/white diffraction etc. Plenty there that is not crystallography. Yes? Ldm1954 (talk) 04:30, 18 April 2024 (UTC)

Perhaps approaching this from the reverse direction would help clarify the possibilities: reorg this article to more clearly identify the XRD content. In other words, the current article looks like x-ray crystallography with some muddiness from XRD, but if the XRD part were clearer then it would look like two articles that should be split. Johnjbarton (talk) 15:03, 18 April 2024 (UTC)

We have an existing powder diffraction article that seems quite detailed and includes X-ray as well as other types of radiation, and a few other diffraction-related articles. I like Johnjbarton's idea of keeping this X-ray crystallography article on its named topic and working on moving content not strictly on that topic to other articles (maybe even new ones). Maybe a start would be X-ray diffraction as a WP:SUMMARYSTYLE parent of powder diffraction, X-ray crystallography, X-ray scattering techniques (which itself is a parent of SAXS, WAXS, etc.), etc. That could help us find better homes for content here that is not on this article's narrowed topic. DMacks (talk) 15:42, 18 April 2024 (UTC)

For DMacks mainly, X-ray scattering is (and should remain) the overall summary as it includes both elastic and inelastic. X-ray crystallography is all about solving, PXRD is different (and I know ICDD want to rewrite that page). Small steps to clean a massive area.

As a very rough guide, see User:Ldm1954/Sandbox/XRD for what would be removed from this article and form the core of an XRD page. Very rough Ldm1954 (talk) 03:35, 19 April 2024 (UTC)

I am reviving X-ray diffraction (as stated on the crystallography page as well as here and a couple of other places for discussion some time ago), moving selected material from X-ray crystallography, where contributors can be found. More work is needed, this is just the first pass. Ldm1954 (talk) 07:59, 1 May 2024 (UTC)

I suspect that they are used, often enough, synonymously, even if technically they should not be. For one, it is still crystallography on amorphous, or non-crystalline solids. Someone once claimed that crystallography is the best path to a Nobel prize, based on statistics of prize winners. On the other hand, it might be that this one is long enough for two articles. It is crystallography if done by a crystallographer, even if not done on crystals. Gah4 (talk) 11:42, 1 May 2024 (UTC)

Sorry, as a professional crystallography I need to point out that this is not right. X-ray diffraction is diffraction using X-rays, similar to electron diffraction. X-ray crystallography is crystallography using X-rays, comparable to electron crystallography. Diffraction is an elastic process with photons, matter waves etc. Crystallography is about determining atomic positions, it is not about mineral crystals despite the name.

N.B., yes, there have been many nobels in X-ray crystallography, and relatively few (von Laue, the Braggs) for X-ray diffraction,see the list in the article. Ldm1954 (talk) 12:02, 1 May 2024 (UTC)

OK, but what do you do with X-ray diffraction other than X-ray crystallography? One of the more amazing things to me, is that the lattice constant of silicon is known to 10 significant digits. Maybe you don't count measuring that as crystallography, though. Gah4 (talk) 19:58, 2 May 2024 (UTC)

Many other uses beyond crystallography, for instance phase identification by comparison, determination of the composition of mixtures, thermal expansion, disorder, phase transitions, texture, orientation, epitaxy..the list is long and there is much more than I have listed. Ldm1954 (talk) 05:48, 3 May 2024 (UTC)