Abstract

The expansion process of a supersonic beam is an ideal system to study how thermal equilibrium is established through molecular collisions. Snavery et al. measured the rotational energy distribution of NH₃ in a supersonic beam, and found that the rotational temperature was well-defined in a single K stack, but was critically dependent on K. Higher (J, K) levels were observed to be over-populated at z/D = 11 by Baldacchini et al., where D is the diameter of the nozzle and z is the distance from the nozzle. On the other hand, a thermal distribution was reported by Veeken et al. at z/D<l 1.5.

© 1992 IQEC