Far infrared spectra of H2 in liquid Ar and memory effects in the translational bands

The spectra of dilute solutions of normal hydrogen and pure parahydrogen in liquid argon have been measured in the spectral range 12–700 cm−1. From such spectra we have obtained the rototranslational profile and the pure translational band of orthohydrogen and parahydrogen dissolved in liquid argon. The low frequency part of the spectrum measured in the solutions of parahydrogen in liquid argon is dominated by the intercollisional interference effects, which are discussed and compared with those previously observed in solutions of Ne and He in liquid Ar using a simple model for the motion of the solute in the liquid.