Infrared Band-Shape Studies of Sulphate Glasses *

Several vibrational band-shape studies which have used either Raman or infra-red (IR) spectroscopy have been reported in the literature [1—3]. With very few exceptions [4,5], however, the studies have generally been performed on symmetrical molecules in non-viscous fluids. In such situations molecular motions may be characterized with little ambiguity [6]. Translational and rotational motions of groups generally lead to a broadening of the vibrational bands. It is in fact possible to show that the bandshape (/(co)) is the Fourier transform of the correlation function, cp (t), of the transition dipole moment at times 0 and t. I (co) can be expressed as