![]() The latter is resonantly enhanced when the frequency difference between the pump and the Stokes beams (ω p-ω S) coincides with the frequency of a Raman resonance, which is the basis of the technique's intrinsic vibrational contrast mechanism. These beams interact with the sample and generate a coherent optical signal at the anti-Stokes frequency (ω pr+ω p-ω S). CARS is a third-order nonlinear optical process involving three laser beams: a pump beam of frequency ω p, a Stokes beam of frequency ω S and a probe beam at frequency ω pr. ![]() As a result, CARS is orders of magnitude stronger than spontaneous Raman emission. Unlike Raman spectroscopy, CARS employs multiple photons to address the molecular vibrations, and produces a coherent signal. ![]() ![]() It is sensitive to the same vibrational signatures of molecules as seen in Raman spectroscopy, typically the nuclear vibrations of chemical bonds. ![]() WikiMili Coherent anti-Stokes Raman spectroscopy Last updated August 26, 2021Ĭoherent anti-Stokes Raman spectroscopy, also called Coherent anti-Stokes Raman scattering spectroscopy ( CARS), is a form of spectroscopy used primarily in chemistry, physics and related fields. ![]()
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