STATE-TO-STATE VIBRATIONAL-ENERGY TRANSFER IN DF(V=1-3)

Overtone vibration-laser double resonance studies of DF(v = 1-3) energy transfer yield self-relaxation rate constants for v = 1, 2 and 3 of k 1 = (0.37 ± 0.06)×10-12 cm3 mol-1 s-1, k2 = (22.0 ± 2.0)×10-12 cm3 mol-1 S-1, and k3 = (17.0 ± 1.8)×10-12 cm3 mol-1 s-1 , respectively. The approach also directly measures the relative importance of vibration-to-vibration (V-V) and vibration-to-translation-and-rotation (V-T,R) energy transfer. The fraction of DF(v) molecules relaxing by V-V energy transfer is 1.1 ± 0.1 and 0.72 ± 0.10 for v = 2 and v = 3, respectively. Essentially all of the vibrational energy transfer in v = 2 occurs via the V-V mechanism. The slower relaxation of DF(v = 3) compared to DF(v = 2), in contrast to simple scaling law predictions, reflects the decreasing influence of the V-V mechanism, even though it is still the primary relaxation pathway for DF(v = 3). Comparison with HF self-relaxation qualitatively indicates that V-R energy transfer is important in V-T,R relaxation of DF (v = 1 ). © 1990 American Institute of Physics.