TIME-RESOLVED COHERENT RAMAN-SPECTROSCOPY CONTROLLED BY SPECTRALLY TAILORED NOISY LIGHT

A new type of frequency-and time-resolved coherent Raman scattering (C RS) spectroscopy using broadband non-transform limited noisy light is presented. The noisy light source is designed to have a doubly peaked spectrum, and the signal [called I-(2)CRS(3c)] is observed to be simil arly double peaked with one of the peaks being a new three-color 'hybr id.' Time resolution of the order of 100 fs is achieved by interferome tric manipulation of the noisy light in the sample. Up-conversions and down-conversions of the vibrational transition frequency being studie d [the 655.6 cm(-1) vibration of CS2(1)], called radiation difference oscillations, are observed in the interferometrically time-resolved co ordinate. It is shown how the oscillations and their decay can be expl ained in terms of spectral 'filtering' of the noisy light involving th e vibrational resonance of the sample. (C) 1997 John Wiley & Sons, Ltd .