The vibrational spectra of phosphine and arsine in the liquid state

The vibrational spectra of liquid PH3 and AsH3 were studied in the region o f fundamental vibrations in a wide temperature range. The time correlation functions of vibrational and rotational relaxation were calculated and the characteristic times of these processes were determined. In the polarizatio n Raman spectra, the v(iso) and v(aniso) frequencies of, in particular, the nu(2)(A(1)) mode did not coincide. The conclusion was drawn that, in liqui d hydrides, not only resonance exchange of vibrational energy but also asso ciation processes may make a considerable contribution to the frequency dif ference between the isotropic and the anisotropic Raman line components.