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 σ_{ν 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.