Knowledge Bank

Using high resolution Raman gain spectroscopy, we have measured the broadening and shifting of Q(0) to Q(2) lines in $D2$ and $D2$-He mixtures at 250K, 200K, 150K, and 100.7K. at each temperature, the linear broadening and shifting coefficients were extrapolated to the case of infinite dilution, and compared with theoretical calculations. The calculated broadening and shifting coefficients are in a good agreement with our precise measurements. The diffusion constants extracted from the linewidths are in agreement with mass diffusion constants at different temperatures. We have also observed a deviation from soft collision model in $D2$ and $D2$-He mixtures at low densities.