PICOSECOND TO MINUTE MOLECULAR VIBRATIONAL DYNAMICS IN CRYOSOLIDS

Recent studies of the vibrational energy relaxation of molecules dispe rsed in cryogenic rare gas and nitrogen matrices are reviewed. They ha ve been carried out using either benchtop tunable IR lasers or the Ors ay Free Electron Laser Clio. They include laser-induced vibrational fl uorescence and pump-probe studies of NO and O-2 in solid Ar and Kr, vi brational stimulated emission of (CO2)-C-13 in argon, and picosecond p ump-probe and IR photon echoes of W(CO)(6) in Ar and N-2. Vibrational relaxation times range from 30 min for O-2 (v = 1) in the Ar matrix to 20 ps for the T-1U CO stretching mode of tungsten hexacarbonyl in sol id nitrogen, reflecting a variety of radiative and radiationless proce sses.