Raman scattering has been observed from both the external and internal motions of the molecules in each of the four condensed phases of oxygen. The stretching vibration gives rise to a sharp band at 1552.5cmminus;1in each phase. Weak wings occur at the base of this band in theggr;and liquid phases. Librational lattice modes are observed at 44 and 79 cmminus;1in theagr;phase and at sim;thinsp;50 cmminus;1in thebgr;phase. The intensities of these bands relative to that of the internal fundamental are in reasonable agreement with those expected from the oriented gas model. Inggr;hyphen; and liquid oxygen, the external motion gives rise to strong wings on the Rayleigh line. Estimates of the meanhyphen;square torsional amplitude and the torque acting on the molecule have been made from the observed lowhyphen;frequency spectra, and indicate that the torsional motion is highly hindered in each phase. The roothyphen;meanhyphen;square torsional amplitude increases from an average of 9deg; in theagr;phase to 18deg; in the liquid.
展开▼
