Talk:Raman spectroscopy

message: * I like the tennis ball + spring system analogy presented below. It could be cleaned up and with a few diagrams could make this article much more approachable to newcomers like myself. 68.126.187.239 (talk) 08:46, 9 April 2012 (UTC)
thread_title:  Lots of thoughts/questions 

message: Can somebody explain what a "virtual energy state" is?  How is this distinct from a "true" energy transition (presumably one where the electrons are moved to an excited state)?
:Since any wavelength radiation can theoretically cause the Raman effect, it then follows that the excited state most of the time does not correspond to any electronic/vibrational/rotational energy level.  That is why the term "virtual energy state" is used. Mill haru 01:54, 8 January 2007 (UTC)
replies: text: Can you provide a more thorough explanation or direct a link its explanation? I'm having trouble visualizing this virtual effect. Thanks. LostLucidity (talk) 19:44, 27 January 2008 (UTC)

text: In general the incident photon has far more energy than the difference between the ground state and the excited state.  (In something like infrared spectroscopy, the incident photon has an energy equal to this difference and can be absorbed when the transition occurs).  Thus the photon cannot be completely absorbed by causing the excitation.  In essence therefore what happens is that the incident photon loses some of its energy and comes out at a lower frequency.  However, in quantum mechanics we talk about transitions absorbing or emitting a photon with energy equal to the energy difference of the transition.  To apply this language here, the ground-state electron must absorb the incident photon and move to a ridiculously high energy state, and then immediately emit a slightly less energetic photon, and move down to an excited state.  It seems doubtful that this actually happens, and so they call it a virtual energy state, presumably because it sounds more impressive than `ridiculously high energy state'.  It's a didactic model more than anything. 131.111.74.86 (talk) 16:29, 5 June 2008 (UTC)

text: Do you mean that the essence of the Raman effect still not clearly when using "virtual energy state" model to explain. I still wonder about the nature of the phenomenon. Could you explain it with out "virtual energy state"?. In flourescence, UV photons are absorbed and the molecule has a "ridiculously high energy state". So I think that a high energy state is very common.  —Preceding unsigned comment added by 118.71.67.38 (talk) 06:10, 21 October 2008 (UTC)

text: Spectroscopists a weird bunch and as such decide to use wierd units, in this case the Wavenumber. They also tend to use the terms energy, wavelength, wavenumber and frequency interchangebly, since they all are related to energy. In Raman spectroscopy what is measured is the difference in energy between the scattered light and the excitation source, and the amount of energy involved is characteristic of a particular bond. For example, silicon has a primary band (or peak) at a Raman shift of about 520 /cm, and that is irrespective of the wavelength of the laser. A skilled spectroscopist will be able to tell simply from looking at a spectrum the major components of a sample as certain bands and features tend to correspond to specific Functional_groups --Wound 22:50, 4 Apr 2005 (UTC)

text: I reworded it to fix these problems. the wub "?!" 10:40, 4 July 2007 (UTC)
thread_title: Virtual energy state

message: Hi every one, I would say that I am not completely agree with  the example proposed to describe the lateral and depth resolution for a Raman   microspectrometer. </br>
First, about the lateral resolution of 250 nm. I think that a lateral resolution of 250 nm could be reached but not with a confocal microscope only. For your example, with a conventional Raman microspectrometer equipped with a He-Ne (632,81 nm) and a dry microscope objective of x100 (Numerical aperture = 0.9), the best lateral resolution you could have is around 1 micrometer. I think a resolution of 250 nm can be reached on AFM instrument coupled with a Raman spectrometer.</br>
Secondly, the depth resolution depend on the nature on the sample. On a Si Wafer, the depth resolution is closed to 1 µm. On bone, the depth resolution decrease to 5 µm. It depends on the homogeneity of the sample. Generally, in spectroscopist review, everybody agree that the depth resolution is close to 1 µm. </br>
If you want, I have reference concerning the use of Polarized Raman experiments in order to determine apatite crystals orientation in human  teeth. 
Capsulcorp (talk) 15:16, 27 June 2008 (UTC)
replies: text: Isn't the phrase "very high spatial resolution" in fact dubious? For example, X-Ray nanotomography offers resolution down to 50 nm; SEM (okay, rather destructive as we often need to prepare the sample) – easily down to 20 nm. Or this is maybe for non-destructive methods only?--Esmu Igors (talk) 18:22, 15 January 2013 (UTC)
thread_title:  Comment about lateral and depth resolution 

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thread_title: Image copyright problem with File:CVRaman.jpg

message: A citation for use of Raman spectroscopy with a wide range of excitation wavelengths is currently Reference [14], but this citation seems to be actually about biomedical imaging. This citation numbering issue should be investigated/resolved.  — Preceding unsigned comment added by Slepkov (talk • contribs) 16:43, 14 October 2011 (UTC)
thread_title:  Suggestions 

message: Isn't there a slight mistake in that image? As far I know the selection rule for IR-spectroscopy is v = ± 1 (not 2)!
:(regarding also another comment above)
: The selection rule is ±1 only for the harmonic oscillator (when a system vibrates just like a spring, according to the Hook's law). For anharmonic oscillator (usually described by the Morse curve) this is not true, and ±2, ±3, etc. are all allowed. But, of course, as these refer to exciting to higher states, often with different symmetry than that of dipole moment components (in IS) or polarizability [tensor] components (in Raman), transitions should be less probable.--Esmu Igors (talk) 18:07, 15 January 2013 (UTC)
thread_title:  Image - Raman Energy Levels 

message: I'm just reading the article and encountered the term "rovibronic", which is explained after used. That term isn't in Dictionary.com and a lot of other word dictionaries. It might be a bit obscure for casual readers - it's complete jargon. While technically correct and the correct term, consider rewording the passage using different terms to be better understood by a less-technical reader.  — Preceding unsigned comment added by 71.241.129.12 (talk) 23:16, 13 December 2016 (UTC)
replies: text: This is the usual term, but it can always be better explained. I have now added a wikilink pointing to the article on Rovibrational coupling. This may help clarify the term a little for the reader. Dirac66 (talk) 00:05, 14 December 2016 (UTC)
replies: text: Hmm. I seem to have forgotten the "onic" which is short for electronic. I have now redirected the link to Rovibronic coupling, and also added "rotational-vibrational-electronic" in parentheses. Dirac66 (talk) 18:20, 5 July 2019 (UTC)
thread_title: Rovibronic?