Knowledge Bank

Collision-induced infrared absorption spectra of the double transitions of $H2(v=0\to 1)$ and $D2(v=0\to 1)$ have been observed at 77 K and 201 K for the first time in the spectral region 7000 - 8000 $cm-1$. The spectra were recorded with a 2 m absorption cell for total gas densities up to 550 amagst with partial gas density ratio of 1:1 of $H2$ and $D2$ at both temperatures. The observed transitions at 77 K, for example, are interpreted in terms of the following transitions: \begin{eqnarray*} Q_{1} (1,0) of H_{2} + Q_{1} (2,1,0) ofD_{2},\ Q_{1} (1,0) \ of \ H_{2} +S_{1} (0)\ of\ D_{2},\Q_{1} (1,0) of H_{2} + S_{1} (1) \ of\ D_{2},\S_{1} (0) \ of\ H_{2} + Q_{1} (2,1,0) \ of\ D_{2}, \ and\ \ S_{1} (1) of H_{2} + Q_{1} (2,1,0) \ of \ D_{2}. \end {eqnarray*} Analysis of the experimental absorption profiles will be presented using two different line shapes proposed in recent literature. The absorption coefficients, line-shape parameters, etc., obtained from the analysis will be also presented. The present spectra of $H2+D2$ will be compared with those obtained for $H2$ at 77 K and $D2$ at 77 K in their first overtone regions and the arising problems will be discussed.""