FEMTOSECOND DYNAMICS OF I-2(B (3)-PI(0U)-SPECTRA() IN LIQUIDS FROM RESONANCE RAMAN)

The intensity distributions in the overtones of resonance Raman spectr a for I-2 in liquid CCl4 and Xe are presented for several excitation e nergies in the bound part of the B 3 Pi(0u)(+) state. In liquid CCl4, the decrease in intensity with v'' is monotonous and for all excitatio n energies similar to that of a free wave packet in the gas phase. A d ephasing time shorter than the round trip time of 300 fs and a dephasi ng process which occurs beyond 3 Angstrom is inferred, in accordance w ith predissociation to the a or a' states earlier proposed. The intens ity distributions in liquid Xe contain a fast decay and a plateau and the strength of both contributions varies with excitation energy. For low v' in the B state a predissociation to the B'' 1 Pi(1u) state with in 40 fs in the range of internuclear distances between 2.78 and 2.85 Angstrom is observed which is less pronounced for large v'. The wave p acket moves undistorted beyond the crossing with the B'' state up to 3 Angstrom.