Off-resonant excitation of molecular vibrations in liquids, investigated by picosecond probe scattering

1432-0649

35.80 ; 42.65 ; 78.30

Springer Online Journal Archives 1860-2000

Physics

Abstract The coherent excitation of molecular vibrations in liquids via off-resonant stimulated Raman amplification is shown to consist of two parts with vastily different spectral and temporal properties. One component situated at the frequency differenceω L −eω S of the driving fields follows almost instantaneously the system response function. The second part at the eigenfrequency eω 0 carries information on the vibrational dephasing. Detecting both frequency components simultaneously by coherent anti-Stokes probe scattering a novel 2-channel method is demonstrated. The vibrational dephasing time of thev 3-mode of CH3I is directly measured to beT 2=2.6±0.15 ps. This result gives experimental support to the deconvolution techniques required in conventional spectroscopy.

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