Vibrational relaxation of NO (v=1) by NO, N2, CO, HCl, CO2, and N2O from 300 to 600 K

Abstract

The vibrational relaxation of NO, laser-excited to v=1, in collisions with NO or with other molecules, M=CO, N2, HCl, CO2, and N2O, has been studied by the laser-induced fluorescence technique, in the temperature range from 300 to 600 K. For the NO–M systems, the relaxation occurs through competitive far-from-resonance V–V transfer and V–T,R deexcitation processes. Measurements of the rate constants governing the temporal decay of the fluorescence intensity emitted by the laser-excited NO molecules were performed as a function of the molar fraction of NO. From these measurements, and those previously obtained on the same NO–M systems, but with the M molecules excited by laser, separate values, even if crude in some cases are deduced for the V–V transfer and V–T,R deexcitation rate constants. Except for NO–N2 and NO–CO, the efficiency of the V–T,R deexcitation of a molecule by collision on another one is shown to be as important as, or even greater than that of the V–V transfer from this molecule to the other one. For both NO–N2O and NO–CO2 systems, the experimental values of the V–V transfer rate constants are compared to values calculated on the basis of long-range multipolar interactions.