Talk:Raman spectroscopy
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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)
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- 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)
- 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)
Can someone provide more information on the following statement: "the lateral and depth resolutions were 250 nm and 1.7 µm, respectively, using a confocal Raman microspectrometer with the 632.8 nm line from a He-Ne laser with a pinhole of 100 µm diameter." The microscopic magnification would be an important piece of information if these resolution numbers are to be reproduced. Mill haru 02:24, 8 January 2007 (UTC)
What does it mean that "The fingerprint region of organic molecules is in the range 500-2000 /cm"? If wavelengths are in units of length then why is the "fingerprint" given in inverse length?
- 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)
This article could use some reorganizing: history should come before applications and applications should be merged with Raman microspectroscopy, other types, and see also. Additionally, at least in the RR article, there is a significant amount of repeated information, which may be more appropriately placed the main Raman article. Finally, the theory section should be expanded or an advance theory section should be added to do this topic justice.--Bjsamelsonjones
I think an experimental set-up section would also be a good idea. Including monochromatic incident light, reflection of the sample, filter to remove the rayleigh scattered light of the same frequency as the incoming light (which constitutes the bulk of the reflected light) a disperser (I think), and a detector. What disperser is used nowadays? Do practitioners use a michelson interferometer and fourier transform like in infrared spectroscopy? 131.111.74.86 (talk) 16:36, 5 June 2008 (UTC)
This is a strange sentence: "Consequently in vivo time- and space-resolved Raman spectroscopy is suitable to measure cells, proteins, organs, and erythrocytes." First of all, what is meant by "measuring" cells or organs? Measuring the quantity or characterizing their chemical composition? Secondly, erythrocytes are a type of cell, so to say that Raman spectroscopy is suitable for measuring cells AND erythrocytes is redundant. —Preceding unsigned comment added by 69.181.124.113 (talk • contribs)
