Coherent anti-Stokes Raman spectroscopy

<p>Coherent anti-Stokes Raman spectroscopy, also called Coherent anti-Stokes Raman scattering spectroscopy (CARS), is a form of <a href="/facts/Spectroscopy/mj71FuNK">spectroscopy</a> used primarily in <a href="/facts/Chemistry/SrNqkGVm">chemistry</a>, <a href="/facts/Physics/a7aH2y08">physics</a> and related fields. It is sensitive to the same vibrational signatures of molecules as seen in <a href="/facts/Raman_spectroscopy/XY063k29">Raman spectroscopy</a>, typically the nuclear vibrations of chemical bonds. Unlike Raman spectroscopy, CARS employs multiple photons to address the molecular vibrations, and produces a <a href="/facts/Coherence_(physics)/NF1Rgdoa">coherent</a> signal. As a result, CARS is orders of magnitude stronger than spontaneous Raman emission. CARS is a third-order <a href="/facts/Nonlinear_optics/maerngXd">nonlinear optical</a> process involving three <a href="/facts/Laser/jk6PTvvT">laser</a> beams: a pump beam of frequency ωp, a <a href="/facts/George_Gabriel_Stokes/7RHJJ5Lj">Stokes</a> beam of frequency ωS and a probe beam at frequency ωpr. These beams interact with the sample and generate a coherent optical signal at the <a href="/facts/Stokes_line/kk568kTg">anti-Stokes</a> frequency (ωpr+ωp-ωS). The latter is resonantly enhanced when the frequency difference between the pump and the Stokes beams (ωp-ωS) coincides with the frequency of a <a href="/facts/Resonance_Raman_spectroscopy/ojudjLWq">Raman resonance</a>, which is the basis of the technique's intrinsic vibrational contrast mechanism.
</p><p>Coherent Stokes Raman spectroscopy (CSRS pronounced as "scissors") is closely related to Raman spectroscopy and lasing processes. It is very similar to CARS except it uses an anti-Stokes frequency stimulation beam and a Stokes frequency beam is observed (the opposite of CARS).
</p>

Coherent anti-Stokes Raman spectroscopy open-in-new

Coherent anti-Stokes Raman spectroscopy