THE INFRARED SPECTRUM OF SOLID HYDROGEN-DEUTERIDE

The infrared spectrum of solid HD has been obtained using a Fourier Transform Spectrometer at a resolution of 0.04 cm('-1). The (DELTA)J = 4(U) and (DELTA)J = 5(V) transitions in the pure rotational and vibration-rotation regions have been observed for the first time. The measured wavenumbers are 885.18 cm('-1) for the U(,0)(0) and 4472.3 cm('-1) for the U(,1(<---)0)(0) transitions while those are 1318.26 cm('-1) and 4886.66 cm('-1) for the V(,0)(0) and V(,1(<---)0)(0) transitions respectively. An attempt to interpret these transitions by hexadecapolar and by 32-polar induced dipole moments yields theoretical values of the integrated absorption coefficients (alpha) as 1.5 x 10('-15)cm('3)/sec for U(,0)(0) and 1.29 x 10('-16)cm('3)/sec for V(,0)(0) and as 1.27 x 10('-6)cm('3)/sec and 1.43 x 10('-17)cm('3)/sec for U(,1(<---)0)(0) and V(,1(<---)0)(0) respectively. These values are in good agreement with the experimental results.; The (DELTA)J = 3(T) transitions are found to be overlapped by the double transitions, 2S(,0)(0) of HD. However, the T(,1(<---)0)(0), Q(,1(<---)0)(0) + T(,0)(0) transitions have been identified and the integrated intensity for the T(,0)(0) transition calculated.; A dip located at 85.6 cm('-1) in the phonon branch of the U(,0)(0) transition has been observed. The dip is attributed to the anisotropic interaction which couples the J = 1 rotational states with the lattice vibrations.; The integrated intensity of one-phonon branch of the U(,0)(0) transition has been calculated. It is found that the phonon branch absorption profile is not simply related to the one-phonon density of states.