Temperature and density dependence of the linewidths and line shifts of the rotational Raman lines inN2andH2

Abstract

The temperature and density dependence of the rotational Raman linewidths and line shifts for the diatomic molecules ${\mathrm{N}}_2$ and ${\mathrm{H}}_2$ has been measured using stimulated Raman gain spectroscopy. Room-temperature results for the density-broadening coefficients, B, in ${\mathrm{N}}_2$ are compared with ab initio calculations, while the low-temperature (80 and 195 K) results are the first to be reported, to our knowledge. Values of γ in the relation, B∝$T^{\gamma }$, were determined from fits to the data for self-broadening in ${\mathrm{N}}_2$ yielding 0.25<γ<0.39. Foreign-gas (${\mathrm{O}}_2$) broadening coefficients for the ${\mathrm{N}}_2$ transitions were also measured and found to be 10–15 % smaller than the self-broadening coefficients. Our linewidth and line-shift results for ${\mathrm{H}}_2$ are in general agreement with previous measurements.