Induced absorption spectra of the infrared fundamental band of molecular deuterium at 77 K: S1( J)+S0( J) transitions

The collision-induced spectra of the fundamental band of normal D2 in the high frequency region 3200--3700 cm-1 were recorded for gas densities in the range 80--140 amagat at 77 K with a 2 m absorption cell. The contribution to the intensity of the band in this region comes from the high frequency wings of quadrupolar transitions S1( J) and Q1( J)+S0( J) with J = 0 and 1, and from the group of transitions S1(2) and Q1( J)+S0(2) with J = 0, 1, and 2 as well as from the relatively weaker double rotational transitions of the type S1( J)+S0( J); the latter transitions arise from the intermolecular interaction between the anisotropic component of the polarizability of one of the colliding pairs of molecules and the quadrupole field of the other. The experimental profiles were analyzed by assuming appropriate line shape functions and using the theoretical matrix elements of the quadrupole moment, isotropic polarizability, and anisotropy of polarizability of the D2 molecule. From this analysis the characteristic half-width parameters delta/sub q/2 and delta/sub q/4 of the quadrupolar transitions and the binary and ternary absorption coefficients of the S1( J)+S0( J) transitions have been obtained. The experimental value of the binary absorption coefficient of S1(0)+S0(0) is (2.2 +- 0.1) x 10-9 cm-1 amagat-2 and the corresponding theoretical value is 1.53 x 10-9 cm-1 amagat-2