Interference effects in the spectrum of HD: III. The pure rotational band at 77 K for HD and HD–Ne mixtures

Abstract

The pure rotational R(0) transition of HD has been studied in pure HD and in HD–Ne mixtures at a temperature of 77 K and at densities between 3 and 123 amagat. Limited measurements of R(1) in pure HD were also made. A value of 8.18 ± 0.26 D was obtained for the R(0) permanent dipole moment of HD, in reasonable agreement with the theoretical value of 8.3 D. However, no evidence for destructive collisional interference effects at high densities was found, and in fact a slight constructive interference was noted. Thus, these results stand in contrast with those for the fundamental band, and with other recent experiments on the pure rotational band, in which destructive interference was invariably measured.