LASER-INDUCED GRATINGS IN THE GAS-PHASE EXCITED BY RAMAN-ACTIVE TRANSITIONS

Sire report on a new time-resolved coherent Raman technique that is ba sed on the generation of thermal gratings following a population chang e among molecular levels that is induced by stimulated Raman pumping. This is achieved by use of spatially and temporally overlapping intens ity interference patterns generated independently by two lasers. When this technique is used in carbon dioxide, making use of transitions th at belong to the Q branches of the v(1)/2y Fermi dyad, it is possible to investigate molecular energy transfer processes. A further unique f eature of this method is spectral resolution that is better than that achieved by coherent anti-Stokes Raman scattering. (C) 1997 Optical So ciety of America