Talk:Chemical shift
From Wikipedia, the free encyclopedia
 |
This article is within the scope of WikiProject Physics, which collaborates on articles related to physics. | |
| ??? | This article has not yet received a rating on the assessment scale. [FAQ] | |
| ??? | This article has not yet received an importance rating within physics. | |
|
Please rate this article, and then leave comments here to explain the ratings and/or to identify the strengths and weaknesses of the article. |
||
 |
Chemical shift is part of WikiProject Spectroscopy, an attempt to better organize information in articles related to spectroscopy. If you would like to participate, you can edit the article attached to this page, or visit the project page, where you can join the project and/or contribute to the discussion. |
| ??? | This article has not yet received a rating on the quality scale. |
| ??? | This article has not yet received a rating on the importance scale. |
| Comments | Please leave a short summary to explain the ratings and to identify the strengths and weaknesses of the article. |
This chart kind of bothers me. Not because the information presented is inaccurate, but rather that it shows a lot of unexplained information about the different nuclei. If you're going to show the spin number, the magnetic moment, the electric quadrupole moment and so on, don't you think it would be good to explain how these are important? Like for 14N, the electric quadrupole creates such broad signals as to be useless for structure determination compared to 15N? In a lot of ways, this seems like information that belongs in a separate article from chemical shift since for many of these nuclei the typical chemical shift definition using TMS does not apply. Perhaps a separate article from the main article on other NMR nuclei besides proton and 13C NMR would be a more appropriate place to talk about these different nuclei. Otherwise, an addition to the current article about NMR in general would also be useful, but I think as it stands this is somewhat irrelevant to the idea of chemical shift. --Ghiles 23:18, 13 May 2006
the definition of chemical shift was invented to give standard differences in frequencies for different molecules, independently of operating magnetic field. I've come accross the following definition: sigma = (delta - delta_ref)x10^6/delta_ref where "sigma" is the chemical shift "delta" resonance frequency of the molecule of interest "delta_ref" chemical shift of TMS (tetramethylsilane) the result is in ppm as well and does not refer to field strength (or indirectly to frequency) of a magnet. Please take a look at Carlson Centre for Imaging Science covering this topic. (this is my first post to wikipedia) --Witoldmatysiak 20:47, 20 Jun 2005 (UTC)
Hello, That's kind of true: What you've found is the correct definition of a chemical shift (using different letters), see also IUPAC, 2001. The author of the article means the same thing, I would say, and didn't want the equation look to difficult (which, in principle, is a very good thing). Please note that your definition is still dependend on the strength (actually, flux density) of the external magnetic field, because that's what gives you the reference frequency! The chemical shift is indeed usually called δ, but that does of course not change the physics behind it... Maybe I find some time to add a bit to the text some time. Kindest regards, Ksei 04:06, 26 July 2005 (UTC)
[edit] Such language!
The magnetic field of a NMR magnet is static, so what is its operating frequency? What are some units like tesla and gauss? If the nucleus you are observing is Si, isn't that the most important one? —The preceding unsigned comment was added by 24.131.7.107 (talk)
Your first two questions are answered in the NMR Spectroscopy wiki page. I'm not quite sure what your concern is in the third...what and where is the specific wording that you're talking about? DMacks 04:11, 12 September 2006 (UTC)
[edit] The fastest way to..
This section, while perhaps made with good intentions, seems quite out of place on wikipedia. Is wikipedia a textbook for everything? No, I'd say not. Perhaps links to exercises could be placed in the external links, instead of in a part of the article? Shandolad 10:29, 15 October 2006 (UTC)
