Low temperature measurements of the rotational relaxation in D2 free jets

Abstract

The rotational relaxation of molecular deuterium in a free jet expansion has been studied between 78 and 473 K by pseudorandom time-of-flight technique. In the temperature range 78–308 K a decrease of the rotational collision number Zrot with increasing temperature is observed as predicted theoretically by Raff and by Rabitz and Lam. Also reported are room temperature data of Zrot for H2 and HD expansions. The number of collisions required to relax H2, D2, and HD at room temperature is in the ratio 10:5:1.