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The diagram that demonstates the splitting of the electon spin energies is wrong with the lowest energy being negative. This is not the case, in NMR the lowest energy of the split angular momentum is positive in value. Would be great to see this changed if any one still has the original .jpeg. EPR is the spectroscopy that has a negative value for the lowest split energy value 125.238.142.222 ( talk) 10:02, 28 May 2008 (UTC)
Surely depends on nucleus and sign of gamma? — Preceding unsigned comment added by Cowburn ( talk • contribs) 13:11, 6 August 2012 (UTC)
I divided the page sections, and greatly expanded the description of how NMR works. This is the closest I have ever come to giving a quantum mechanics lecture! Please help with any parts that are unclear...
The history section needs better organization, although I'm grateful for whoever put that up there. More discussion of various techniques (FID, spin-echo, CPMG) is necessary, as is discussion of the various factors that are measured by NMR spectroscopy. --hb, 18 Nov 2002
In the history section, it would be nice to add a couple of sentences on the discovery of chemical shift and how Bloch commented that if this were "some nasty chemical phenomenon" it could "terribly impede" the measurment of nuclear magnetic moments. Detials of the story can be found at http://www.ebyte.it/library/hist/ProctorWG_Reminiscences.html Roy Hoffman 11:20, 26 March 2006 (UTC)
The description of the NMR signal as reading the radiation that comes out when the nuclei reequilibrate needs to be removed. This is a common misconception about what the NMR signal is. Both T2 and T2* measurements are made while the nuclei are in disequilibrium; although the bulk magnetization decreases, it is because the signals are going out of phase with each other (because they are resonating at different frequencies), not because the nuclei are reequilibrating. (anonymous, 18 Feb 2004)
Concerning the sentence: "When radio power is sent to the antenna, it generates an oscillating magnetic field H1 (not to be confused with the external magnetic field). "
should this not be "..generates an oscillating electromagnetic field"? Foppe Brolsma, brolsma_produkties (at) hotmail.com
Nuclear spins do not emit radio waves in response to a radio frequency pulse. This mistake has been repeated in so many text books that no doubt many people believe it. David Hoult, an impeccable physicist, made a valiant attempt to correct this misconception in 1989. The reference is: D. I. Hoult, Concepts in Magnetic Resonance, 1989, 1, 1-5. The wise reader will start here. -Jan Wooten
Hm...Nuclear spins do not emit radio waves...so what about radiation damping (a serious problem in NMR spectroscopy on water containing samples)....rather the NMR signal is an interaction between the ensemble of nuclear spins (coherence) and the RF coil which detects the signal..according to energy conservation (1. law of thermodynamics etc.) there must be some kind of emition, this is trivial. It seems to me that people confuse the quantum mechanical and the clasical description of NMR. I agree that NMR is not directley comparable to spectroscopical techniques like fluorescence spectroscopy or similar (because off the large difference in energy), but formally it is correct that the nuclei emit a signal...although only a very smal portion of this signal is measurable. The NMR signal is a macroscopic quantity...but only due to technical reasons. Flogiston 22:44, 6 October 2006 (UTC)
RE: "Nuclear spins do not emit radio waves...": Although this general comment is `true' for both liquids and solids NMR absorption, it is certainly not quite so for the emission of both radio waves and microwaves by resonating protons (Yes, H-1 (+) ions) in oscillating plasmas placed in static magnetic fields, also coupled to electrons in such plasmas, that have been demonstrated repeatedly both experimentally and theoretically to emit both radio waves and microwaves in addition to light!!!
This does not mean, however--as you said and cited-- that one should confuse NMR **absorption** of resonant RF with the above cited phenomenon in oscillating plasmas that involves RF and microwave emission by proton plasma resonances in static magnetic fields. Should you require the relevant references for the above observed emission phenomenon in proton containing plasmas, I will be glad to oblige.
Bci2
Consensus?
Currently the beginning of this article reads:
(NMR) is a property that magnetic nuclei have in a magnetic field and applied electromagnetic (EM) pulse or pulses, which cause the nuclei to absorb energy from the EM pulse and radiate this energy back out. The energy radiated back out is at a specific resonance frequency which depends on the strength of the magnetic field and other factors. This allows the observation of specific quantum mechanical magnetic properties...
Later however, it seems to be suggested that data is generated in NMR spectroscopy by the formation of an electrical current, which, in turn is generated by oscillation in the net direction and instensity of the local magnetization. So whether or not RF-irradiated nuclei absorb and then later give-off radiation (of any-which frequency) is fact or not, it is unclear from this article what is being measured. It seems to me that "the energy radiated back out" from an irradiated nucleus may not directly affect the Free Induction Decay (FID) which is what the spectrometer records. Is this true? Please modify. —Preceding
unsigned comment added by
24.3.17.121 (
talk)
03:54, 15 February 2010 (UTC)
The text in the article's introduction is technically correct, albeit misleading to what NMR actually is. There are two exchanges of information / energy that is transpiring. Spin's are electrical charges that precess and thus one can place a electrically conducting material near the spins and measure a voltage/current induced, i.e. Faraday's law of induction. Spin's in the lower energy state can absorb a photon and align the phase of its spinning with that of the absorbed photon. Coherent photons absorbed by the spins causes coherent precessing and thus a coherent voltage induced in the conductive material, i.e. the information containing signal.
When the spin's transition from a higher energy state to a lower energy state a photon is emitted. Only a small fraction of the photons transmitted into a sample, in an NMR experiment, are absorbed. Only a small fraction of the photons emitted during downward energy state transition make it to an antenna. The induced voltage in the antenna would be prohibitively small.
68.164.8.124 (
talk)
03:36, 3 November 2010 (UTC)
The COSY section should be removed/sidelined until it can be explained better. It reads scattily, as if pulled directly from a textbook, and there are many technical aspects unexplained (double Fourier-transformation, Pulses, how the 2nd dimension arises) and many aspects are poorly written (Example of ethanone). I feel this doesn't make it an asset to this entry.
Any feeling/input on this would be appreciated because its a very major edit! Unless anyone objects I'll be removing it when I edit the theory of this section. (And hopefully have time to put something meaningful in its place). Let me know -- Lee-Jon
The COSY section deals with other aspects of 2D NMR as well and should be part of a separate entry entitled 2D NMR or Two dimensional NMR Roy Hoffman 13:20, 27 December 2005 (UTC)
The How NMR Works section has been renamed to Theory... and consigned to the latter part of the article so not to frighten undergraduates etc. It has been expanded so (hopefully) every concept makes sense and has some theoretical background presented.
Sections I (or you!) want to add are on spin-spin coupling, Pulse NMR & Fourier-transformation, and possibly a brief talk on the nuclear Overhauser effect relevant to NMR. I think that covers almost everything to give some detail on NMR without it being too technical. -- Lee-Jon 21:52, 9 Mar 2005 (UTC)
Thanks for praise. Yeah I agree with the image - it looks much nicer that way -i've amended it and taken the code out of the edit page. Although I feel the COSY section need much refinement, maybe even a major edit to make it a "2D NMR/Experimentation" section. Lee-Jon 21:12, 10 Mar 2005 (UTC)
A layman here trying to understand the theory and I am bother by the use of quantum numbers in the article. In one place, the spin quantum number is call 'ms' (I can't do the formating correctly) and then later it is called 'I'. I realize that one is 'overall' and the other is not but to a layman I cannot tell if that is a real difference (ie a technical term) or if it is something else, especially when other linked articles on quantum dynamics call 'I' something else again. Here is the quote of the beginning and end of the section: "rise to the spin quantum number, ms........... ½ to the nuclear spin quantum number, I." Since I do not know what I am talking about, anyone who edits this, once fixed, please remove my comment. Cheers!
Sorry, layman again. In the following section: "The spin angular momentum of a nucleus can take ranges from +I to –I in integral steps. This value is known as the magnetic quantum number, m. For any given nucleus, there is a total (2I+1) angular momentum states. Spin angular momentum is a vector quantity. The z component of which, denoted Iz, is quantised: Iz = mh/2π where h is Planck's constant." Iz = mh/2Pi but m can be a range of values (from +I to -I, yes?) so how can i determine Iz? Please erase this after correction.
I am an organic chemist and I would describe myself as an experienced user of NMR spectroscopy. I can not claim to be an NMR expert, I could never write my own pulse sequences etc. I also teach introductory organic chemistry, covering the basics of 1D proton and C-13 NMR in the first semester, then students get to run a COSY and a DEPT experiment in their second semester. I am therefore very familiar with explaining the basics of the NMR spectroscopy. It seems clear to me that there are two different topics covered on this page currently
For example MRI (as I understand it) uses the phenomenon of NMR, but is clearly distinct as a technique from NMR spectroscopy.
This difference between physical phenomenon and analytical method has already resulted in there being separate pages for Infrared and Infrared spectroscopy, also Ultraviolet and UV/VIS spectroscopy. See Category:Spectroscopy for other page titles.
NMR spectroscopy is the most widely-used technique in modern organic chemistry and it surely deserves its own page. The spectroscopy page should have less discussion on the theory and physics, and much more on how the technique can be used to analyse molecular structure- things like equivalence, chemical shift, integration, multiplicity, diastereotopic protons in chiral molecules, which nuclei lend themselves well to analysis and which don't, etc. Some of this information is already on this page, much is not. My undergraduate students would currently find almost nothing on this page of value to them. We need this separate NMR spectroscopy page. The COSY section could be part of this new page or could be big enough for its own page. What do others think? Walkerma 07:14, 14 May 2005 (UTC)
PS: I should mention that I have an ulterior motive- we are currently revamping the standard data table for chemical compounds, and we are including a link (for some compounds) chemical shift data or to scans of actual 1H and 13C spectra. The idea is that when you look up (say) limonene, you could click on a link to see NMR data or a spectrum. I would like to have the standard "explanation" link on these tables to lead to a spectroscopy page. Walkerma 07:21, 14 May 2005 (UTC)
I agree, however NMR Spectroscopy extends far beyond Organic chemistry so maybe the page could be written from a few angles:
Unlike UV/VIS and similar techniques, modern NMR Spectroscopy is a very large and very complex area. And as I'm sure you're aware, an end-user approach to NMR is very difficult to discuss without having to delve into some nuclear physics. Any section on NMR Spectroscopy should continually reference a theory section to keep it accurate.
The page has been created here and I'll try and finish a good first build throughout this month! Lee-Jon 09:11, 17 May 2005 (UTC)
Thanks for starting that- it's a nice job so far! Please can I encourage you to keep writing it at a very basic level. I know from teaching this, you only need a very basic understanding of the physics underlying it- just like you don't need to understand general relativity to understand that an apple falls to the ground. I would avoid getting into discussions of T1, T2 etc. on this page if possible. Also, can I recommend that this page be renamed as NMR spectroscopy (small s) (currently a redirect), this seems to be the more usual form when you look at [[ Category:Spectroscopy. I agree that all of those topics need covering- these probably all warrant their own pages. Wikipedia is exploding in size and depth, it seems to me, and with the chemical compounds pages we probably have 500-1000 compounds covered, up from perhaps 100-200 a year ago- so having 10 pages on different aspects of NMR, written at various levels, is totally reasonable. I would suggest that 13C deserves its own page. One small point, should that be "heteronuclear" NMR for 15N etc? Multi to me implies many, which sounds like HETCOR, APT etc. Walkerma 16:53, 17 May 2005 (UTC)
Thanks for the comments. You're right, when I said multi I meant hetero. Typing faster than I'm thinking! Agreed about the small "s". I'll change that. Lee-Jon 09:08, 19 May 2005 (UTC)
I am a bit torn apart in my feelings for splitting up the article on NMR and it's spectroscopic technique. From a scientist's point of view, I oppose this. However, for an Encyclopedia, it's important to be not only accurate and precise, but also brief. Therefore it might be good to proceed to disentangle the "physical phenomenon" and the "spectroscopy", setting the appropriate links. Aside of that, I suggest to write a separate article on solid-state NMR, which may be broken up into two sections describing the effect and the spectroscopy if you show this can be done successfully.
In their 1985 experiment, R. Curl and R. Smalley of Rice University obtained mass spectrum of carbon clusters, where even numbers have large intensities and n=60 is particlularly so (Nature, 1985, 318, 162). They proposed the C60 structure as a soccer ball.
The NMR spectrum of buckminsterfullerene (C60) was published in 1990 by another Nobel prize winner Kroto, H.W. of University of Sussex (J. Chem. Soc., Chem. Commun. 1990, 1423). This confirmed the earlier proposed structure. Indeed, IR spectrum of C60 precedes NMR (Nature 1990, 347, 354). Together, IR and NMR spectra confirmed the structure of C60.
This entry need to be changed to reflect this fact.
I think the article could use a nice diagram of the innards of an NMR machine and an explanation of how the larmor frequency relates to the naming of individual machines (field strength correlation etc.) though, I am not the one to do it. I can't find a good PD diagram of an NMR device so.....any takers?-- Deglr6328 20:11, 18 Jun 2005 (UTC)
Is someone familiar with NMR and NMR spectroscopy in weak magnetic fields and outside of the RF coil, as for oil logging or material science (like the NMR mouse tool that the guys from RWTH Aachen build)? I've heard a couple of interesting talks about it, but I don't feel qualified writing about it. However, I think those are some nice applications in engineering that would extend the "molecular structure" view of the current NMR articles a bit, and may be of interest to readers outside of the field. Would be cool if someone picked that up!
Especially when naming the subpages. I will proceed to rename them in order to conform to the Manual of Style (as well as professionalism)...well, that's my rant of the day, off to formalise dozens of other articles...keep a look out for double redirects. There's something gratifying about the term "magnetic resonance", I don't see why we have to abbreviate it to such a horrible acronym. ;-) Elle vécut heureuse à jamais ( Be eudaimonic!) 00:08, 17 February 2006 (UTC)
...The HNCACO only contains the one from the previous residue, and it is thus possible to assign the carbonyl carbon shifts that corresponds to each HSQC peak and the one previous to that one. Thus it is possible to make the assignment by matching the shifts of each spin system's own and previous carbons. The HNCA and HNCOCA works similarly, just with the alpha carbons rather than the carbonyls, and the HNCACB and the CBCACONH contains...
I've tagged protein nuclear magnetic resonance for cleanup. Can someone convert the acronyms into actual concepts, formalise the page, then remove the tag when done? So basically, acronyms are tolerable, just don't use them in page titles, or use them wantonly. HNCA and HNCOCA need to be converted, too. Elle vécut heureuse à jamais ( Be eudaimonic!) 20:52, 17 February 2006 (UTC)
The main reason for my failing this is the fact that the article tends to blur the difference between NMR the physical phenomenon (the subject of this article) and NMR spectroscopy (the application of said phenomenon, covered mainly in the NMR spectroscopy article). This is understandable because (a) both topics used to be covered on this page and (b) chemists tend to talk about "an NMR" when they mean an NMR spectrum. The applications of NMR in spectroscopy and MRI are important and deserve coverage, but they should not be in place of NMR as a phenomenon. The History section (after the first four paragraphs) reads more like a history of NMR spectroscopy rather than of the study of the phenomenon itself (ironically, the spectroscopy page doesn't include any of this same history!). This is a bit like reading the article on microwaves and finding the history of the development of microwave ovens described, simply because "microwave" in the vernacular refers to the ovens. To someone unfamiliar with the topic, this must be very confusing.
The theory section seems fine - sure, it's technical, but then again this is a pretty technical subject. Terms are explained as they should be.
The "Uses" section really needs a single person to rewrite it into a coherent section. It reads like 50 different people have thrown in bits of information - the content is there, but it needs organising and rewriting in places (e.g. the C60 paragraph). I would like to see subsections of Uses
I also suspect there may be some things missing from here, and moving inappropriate spectroscopy stuff elsewhere would create the space for this. I'd like to see listed some of the elements that are most active in NMR. The Nuclear spin and magnets section explains which will be active, but some examples like why 12C is inactive but 13C is active. I'd like to see discussion (in simple terms, perhaps purely qualitative) of the sensitivity of the nucleus - why 1H is easy to see, but 15N is not. Could it include how quadrupolar relaxation can smear out a signal and make it harder to observe with a nucleus like 51V? I'm not knowledgable enough to write this material, but I suspect this article could have a lot more useful content. Walkerma 03:27, 17 June 2006 (UTC)
There is no explanation or Wikilink of what T2 is. It's just dropped in. -- Scottandrewhutchins 22:16, 19 January 2007 (UTC)
Additionally, T2* needs a better description. It is used without explanation
--Evan and Gabe, MIT students doing an NMR experiment
The problem of poor noise-to-signal ratio is mentioned under the CONTINUOUS WAVE SPECTROSCOPY section, and the subsequent need therefore for signal averaging.
As I understand it however, poor noise-to-signal ratio is a problem inherent to the NMR process itself, not just CW Spectroscopy but also FOURIER SPECTROSCOPY. No signal-to-noise aspects are discussed under the FOURIER SPECTROSCOPY section of the article however.
Perhaps the issue of signal-to-noise needs it's own heading and section, separate from CONTINUOUS WAVE SPECTROSCOPY to make things a little more clear.
Pookie69 11:51, 2 April 2007 (UTC)
I cannot find a reference to EFNMR in wikipedia, though there are good web pages about it. I suggest adding a reference to it, and developing an article. GilesW 12:00, 13 April 2007 (UTC)
I suggest adding a link from the NMR article to the Magnetometer article, which discusses PPM and Overhauser magnetometers. I notice that the Magnetometer article does not mention that these are EFNMR effects. Perhaps this should be remedied, once the EFNMR references are in place. GilesW 12:08, 13 April 2007 (UTC)
Why is this not even mentioned? And the article is too big btw. Hard to find necessary things
article reads:"NMR studies magnetic nuclei by aligning them..." Should it not read:"NMR studies magnetized nuclei by aligning them...". Correct or elaborate please, in a strong enough magnetic field all nuclei can be influenced, essentially the flow of energy is directly influenced to produce statistically strong/weak results, albeit lamonistic. anon 203.59.189.244 19:15, 15 June 2007 (UTC)
Help with Zero Field NMR, Earth's field NMR, and Electric field NMR articles needed, please.
Plus a mention in the text of the main article. Earth's field NMR is a poor relation, but significant (bore hole logging, magnetometers etc).
Any thoughts about sorting the 'See Also' list into alphabetical order? GilesW 16:29, 16 June 2007 (UTC)
The wording of the introduction is orientated towards NMR spectroscopy in high-field laborotory environments, and is not applicable to some other applications of NMR. Furthermore it is rather abstract. I propose that the intro be generalised to make it applicable to Earth's field NMR etc.
See above for various references and questions re EFNMR etc.
The following quote is helpful and could be used with attribution or paraphrased:
"... the [stimulating] frequency necessary to cause nuclear transitions is different for each element or isotope. The resonance frequency is found to vary in direct proportion to the applied field (for all magnetic nuclei); thus the larger the magnetic field the larger the frequency necessary to achieve resonance." Kemp, W. ''NMR in Chemistry : a multinuclear introduction'' Macmillan Ist Ed 1986 p6.
In addition, may I suggest something like:
In the laborotory, NMR studies magnetic nuclei by aligning them with a very powerful external magnetic field and perturbing this alignment using a high frequency magnetic field. The resulting high frequency magnetic field generated by the sample in response to the external perturbing magnetic field is the phenomenon that is exploited in NMR spectroscopy and magnetic resonance imaging.
In the Earth's magnetic field, NMR frequencies are in the audio frequency range, and are typically stimulated by applying a strong dc magnetic field pulse to the sample and analysing the resulting low frequency alternating magnetic field. This effect is exploited in some types of magnetometer and on-location EFNMR spectroscopy.
NOTE: The perturbing fields are generated by inductors, so have no electric component. Electromagnets do not generate electromagnetic fields!
GilesW 21:45, 23 June 2007 (UTC)
Something is missing in this article: Bloch equations. TomyDuby 22:52, 3 July 2007 (UTC)
I think the Bloch equations should be added to the article on Relaxation (NMR). They could also be mentioned briefly in this article and in the article on Felix Bloch. For the moment I agree with you that they seem to be nowhere in Wikipedia. Dirac66 ( talk) 20:18, 10 September 2008 (UTC)
Correction - they seen to be nowhere in the English Wikipedia. I have just found de:Bloch-Gleichungen in the German Wikipedia. Would someone care to translate it? I still think it would be better as a section of Relaxation (NMR) rather than as a separate article. Dirac66 ( talk) 20:25, 10 September 2008 (UTC)
I am missing a discussion on these two modes. TomyDuby 23:00, 3 July 2007 (UTC)
A while ago the following paragraph was added (by an unregistered user) to the article on the Rabi frequency:
I am only familiar with the Rabi frequency in the context of atomic physics. I've done a quick google search and it is regularly mentioned on pages concerning NMR. I feel that these are two distinct (although possibly analogous) concepts that probably merit separate articles. Does anyone have any thoughts on this?-- DJIndica 19:43, 23 October 2007 (UTC)
This article definitely lacks information on the phenomenon of resonance. I personally do not understand this subject fully, especially in the resonance section, where I was hoping to learn about it. In this section, all that is said is the conditions under which "resonance absorption" will occur, leaving many ambiguities. Is the resonance here refering to the emitted photon or the precession of the nuclei? Is the absorption dealing with that of the external electric circuit due to this photon? Is the "correct frequency" something which the experimenter controls or is one that is naturally occurring as a result of precession?
I would really appreciate it if someone took the time to answer these questions in the article. -- Wakod2002 ( talk) 08:43, 28 November 2007 (UTC)
I would like to question the deletion by Cubbi (04:56 12 Jan 2009) with edit summary "rv clathrate spam. Keep it to flow assurance and gas hydrate if you must." The word "spam" normally describes advertising material, but that was not the case here. In fact the deletion consists of 2 sentences about the application of NMR to hydrates, and 3 references in the form of external links to scientific journals published by the ACS (American Chemical Society). This seems to me perfectly valid and on-topic material properly referenced. Please explain why it was deleted. If there is no valid reason I think it should be restored. Dirac66 ( talk) 01:59, 13 January 2009 (UTC)
Could someone please explain somewhere in this article the difference between the apparently small population difference between different nuclear spin states for hydrogen nuclei in an NMR machine and the large difference which is frequently said to exist in so called ortho and para hydrogen at room temperature? This is explained at http://en.wikipedia.org/wiki/Spin_isomers_of_hydrogen. As a chemist I find these facts contradictory. 82.231.41.137 ( talk) 07:40, 20 June 2009 (UTC) You are mad. —Preceding unsigned comment added by 203.128.4.254 ( talk) 10:00, 2 September 2009 (UTC)
Is there an NMR analog of fluorescence polarization ? That is, if you have some nmr active molecule(s), with a diameter of, say ~ 1nanometer, in a solvent, the molecules will rotate at a rate that is roughly proportional to their size (neglecting second order effects). If the molecule sticks (binds) to something much larger - say a bacterial cell with a diameter of ~ 1 micron - then the nmr active molecule will now rotate with the bacteria, and this rotatation rate is much slower then the rate for the free molecule. Is there an nmr process which is senstivie to this change in rotation rate ? 65.220.64.105 ( talk) 16:06, 18 August 2009 (UTC)
14N is listed as an element that can be monitored by NMR spectroscopy. Is this correct? 14N is not listed in my resource.
Akita86 (
talk) 22:06, 28 October 2009 (UTC)
:Thanks. Removed (it is not listed because it has spin zero and is thus undetectable by nuclear or spin resonances).
Materialscientist (
talk)
00:07, 29 October 2009 (UTC)
After the above discussion JWB pointed out in an edit summary (16:09, 29 October 2009) that "There are a few unstable nuclides with odd proton and/or neutron number and zero spin." I have now searched the isotope table in my (1979-80) Handbook of Chem and Physics and found one example which is 206Tl with 81 p and 135 n. Dirac66 ( talk) 23:45, 8 November 2009 (UTC)
In the last paragraph of the "Nuclear Shielding" section (2.2.3) there appears to be a distinction made between "isotropic" chemical shift and "average" chemical shift. I think this is misleading, since the molecular tumbling in solution state NMR is usually isotropic (I can't think of any situations where this would not be the case) and hence the anisotropic contributions are all averaged to the isotropic chemical shift. The same is the case in MAS solid state NMR (neglecting sidebands). Any reference to "average" chemical shift I could find was referring to the average isotropic chemical shift of a certain type of structure (alpha helix for example). I didn't do a very thorough search, so maybe I am just used to a different nomenclature. Also, I don't see any reason for average chemical shift to be an article worth creating. If anything I think there should just be a link to chemical shift. And4e ( talk) 21:24, 21 January 2010 (UTC)
A picture of a small (say, 60MHz) box-like NMR would be a good addition. Too many research-grade behemoths already illustrated in the article. Rmhermen ( talk) 20:21, 19 March 2010 (UTC)
I've just registered to wikipedia, so if I'm doing something wrong, sorry.
http://en.wikipedia.org/wiki/NMR#Discovery
It says here that: "Nuclear magnetic resonance was first described and measured in molecular beams by Isidor Rabi in 1938." But it does not mention that he got the Nobel Prize in Physics for that in 1944. After that it says that: "Felix Bloch and Edward Mills Purcell refined the technique for use on liquids and solids, for which they shared the Nobel Prize in physics in 1952" If they are mentioned to have won the Nobel prize, I think Rabi should too. I have 2 wikipedia sorces (is it ok to cite from another wikipedia page?)
http://en.wikipedia.org/wiki/List_of_Nobel_Laureates_in_Physics
http://en.wikipedia.org/wiki/Isidor_Rabi#Career Protosss ( talk) 16:07, 5 June 2010 (UTC)
Shouldn't we put in a section that explains how the very high magnetic fields are actually created? with at least alink to superconduction, superconducting coils, saturation etc.? 194.53.253.51 ( talk) 08:23, 2 November 2010 (UTC)
The page contains a lot of applications of NMR and details associated with it. i dont think think that pre university students will appreciate it very much. There must have been a sound explanation on whatEXACTLY happens during the phenomenon.
At the top, it says that NMR redirects here. That's no longer true; when I type NMR into the search bar it takes me straight to the disambiguation page. I don't know how to remove that little notice. Jojojlj ( talk) 17:27, 2 May 2011 (UTC)
This article talks the physics but not parts of the machine. I am curious of the scanner of radio waves and can't find info.-- Ericg33 ( talk) 23:01, 23 August 2011 (UTC)
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It's really hard to cover such a huge subject at a sensible level in an encyclopedia; I admire those who've tried. The theory section "Nuclear spins and magnets" tells us that protons pair, and neutrons pair, but proton spins do not pair with neutron spins. Since protons and neutrons both have spin 1/2, we have a nice model for all isotopes with odd-proton having 1/2 spin, odd-neutron having 1/2 spin, and odd-both having 1 spin (both even = spin zero). The model is illustrated by isotopes of hydrogen. But then there is a throw-away comment that 27Al has a spin of 2.5, without explanation. There is also some mention of radioactivity, implying that radioactive isotopes don't follow the normal rules, but no explanation of why/how they differ. Is it worth enlarging on either of these? 149.155.96.5 ( talk) 12:09, 20 February 2012 (UTC)
Thom5738 ( talk) 05:53, 26 February 2012 (UTC)
I have now twice removed an additional image and extensive caption from the "Spin behavior in a magnetic field" section. The image itself is incorrect as it represents the two possible orientations of the magnetic fields (high- and low-energy) with the fields at a skewed angle, which is not correct for the "real-world analogy" being discussed. The caption is redundant to the article itself (see WP:CAPTION). And it's also in general confuses the idea of energy-level splitting based on the two extreme orientations of a real-world magnet (parallel vs antiparallel) with the fact that a magnet can have any arbitrary orientation (basic physics can explain the function of magnetic attraction/repulsion based on field angles). Quantum spin does have two discrete states, but that removes it from the realm of simply rotating a magnet arbitrarily. As the WP:POV beginning of the caption that I removed noted, quantum mechanics is difficult to imagine, but taking an analogy beyond where it is still close to the facts is not helpful. DMacks ( talk) 12:49, 29 July 2012 (UTC)
The caption was really extensive, thank you for shortening it.
Dear All,
The T2 animation is really good. There is however a problem, as I believe the spin should realign with the opposite movement after the 180 degree pulse. I.e. they should come together at the right side, just as they were after the 90 degree pulse.
Best regards,
Rune S Jacobsen — Preceding unsigned comment added by 88.151.179.18 ( talk) 05:06, 2 October 2012 (UTC)
In the second section of the article (Theory of nuclear magnetic resonance) the symbol "S" is used to denote the intrinsic nuclear spin. While it is true that S is used for the spin quantum number of an electron, or other elementary particle for that matter, "I" is typically used to denote the nuclear spin angular momentum, and I will edit the article to that effect in the near future. I have in front of me two seminal textbooks on NMR: Abragam (1973 edition), and Corio (1967 first edition). On page one, Abragam writes: "Many atomic nuclei in their ground state have a non-zero spin angular momentum Iħ (integer or half integer in units of ħ and a dipolar magnetic moment μ = γħI collinear with it." On page 13, Corio gives a more detailed explanation for this use of I for spin angular momentum rather than S, because atomic nuclei are composite particles... As with this page: [2]. Anyway, if there are any objections, raise them, because otherwise S is going away and getting replaced with I. Cheers - 137.53.91.235 ( talk) 21:36, 2 March 2016 (UTC)
The comment(s) below were originally left at Talk:Nuclear magnetic resonance/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.
NMR is a multiple Nobel-prize winning subject in physics and has huge implications in medicine. Its a more advanced and convoluted topic, however, and I think it deserve High but not Top priority for this reason.
==Comment== This 'convoluted' comment does not seem valid at all; the subject is not convoluted; it has been merely poorly explained, and it should indeed have a Top priority. Higher quality edits are needed not a downrating of its importance, which is indeed a Top priority! Nu 09:40, 1 March 2009 (UTC)Bci2Nu 09:40, 1 March 2009 (UTC) february 28, 2009, 3:41 [UTC]. This article still needs work in order to be helpful at a glance: better formatting and more precise wording. Progress has been made since the article failed GA nomination in June. BailesB 20:06, 4 December 2006 (UTC) |
Last edited at 14:56, 5 September 2009 (UTC). Substituted at 01:35, 30 April 2016 (UTC)
Hello, I have ran across this article two times and each time I find the sentence with the term "spin−1/2" confusing as it appears to be stating that the spin for the proton and the neutron are negative. I suppose it would be nice to link to the wiki article on spin-1/2 and maybe reword the sentence so that it is clear that the reference to spin-1/2 means particles that have a net spin of 1/2. I appreciate the reference to fermions, which should make it more clear that the reference is not to negative 1/2, but not everyone is going to realize that the fermion reference will clarify the ambiguity that is present. As such, I think that
PinkAppleFlower ( talk) 21:10, 26 January 2017 (UTC)
The article presently has the sentence in the History section: Yevgeny Zavoisky likely observed nuclear magnetic resonance in 1941, well before Felix Bloch and Edward Mills Purcell, but dismissed the results as not reproducible. I do not understand the point of this sentence in this article. I offer no assessment or challenge to its authenticity, it just seems to me to serve no point to the article. The issue is in that gray area in writing, which is choice of material. Or, if you like, the statement does not seem "notable" to me. It has the sense, now cliché, of statements that Russians did it all first. In short, delete? Bdushaw ( talk) 01:56, 5 September 2022 (UTC)