Temperature dependence of near resonant vibration → vibration energy transfer in HCl–D2 mixtures

Abstract

Laser-excited vibrational fluorescence measurements have given rates for nearly resonant vibrational energy exchange between HCl and D2 molecules over the temperature range of 196–343°K. The energy transfer cross section σν ν shows an inverse temperature dependence; namely, decreases as temperature increases. The magnitude and temperature dependence of these cross sections could be fit by first order calculations based on quadrupole-quadrupole, and dipole-quadrupole interactions. The rates of vibrational deactivation of HCl by He were found to increase with temperature. However, the results on HCl self-relaxation also show an inverse temperature dependence over this temperature range studied. This enhancement observed at lower temperature is probably caused by the attractive chemical forces exerted between HCl molecules.