Vibrational relaxation of the bending modes of D2O, D2S, and H2Se gas mixtures

The method of laser-excited vibrational fluorescence has been used to measure vibrational relaxation of the bending modes ν2 of H2Se and D2S in gas mixtures at 295 K. For H2Se relaxed by H2Se, H2, D2, He, and N2 rates of 30±2, 11±1, 3.4±0.2, 1.5±0.1, and 1.1±0.1 (all×10−13 cm3 molecule−1 s−1 were found). For D2S relaxed by D2S and by N2, rates are 5.5±0.6 and (0.12–0.37) (both ×10−13 cm2 molecule−1 s−1). Fluorescence from HDO (ν2) following excitation of D2O (ν2) gave a rate for vibration–vibration transfer of a bending quantum from D2O to HDO of about (1.4±0.6)×10−11 cm3 molecule−1 s−1. D2O (ν2) is relaxed to translation and rotation at approximately the same rate by HDO as by D2O.