Shock-Tube Study of Vibrational Relaxation in Nitrous Oxide

Abstract
The vibrational relaxation of nitrous oxide has been investigated by following the density changes occurring behind incident shock waves using a Mach–Zehnder interferometer. Measurements made up to an equilibrium temperature of 1700°K (Mach 7) show that neither the symmetric stretching mode nor the asymmetric stretching mode has a significantly longer relaxation time than the bending mode. The rate of relaxation has been measured as the gas relaxes towards equilibrium. During this process, the translational temperature of the gas falls, and it has been found that this fall in temperature will account for the observed increase of the relaxation time. Relaxation times have been measured from 320° to 850°K.