Low-Frequency Spectra and Change of State

D. H. Whiffen
1960 Proceedings of the Royal Society A  
The m ajority of contributions to the Discussion have been concerned w ith th e ! ultra-violet and infra-red spectral regions, b u t im portant considerations also arise! a t lower frequencies. These have been less fully studied because of experimental § difficulties, b u t experiments show th a t changes in the spectrum consequent on* change of state m ay be quite large. In the gas phase, rotational energy levels are usually described in quantum -! mechanical language in term s of the angular
more » ... m s of the angular momentum. In the liquid phase the equivalent levels are not quantized and the motion can be treated on classical lines ! in terms of a frictional coefficient and a rotational relaxation time. Form ally the Debye (1929) dielectric loss formula m ay be derived (Whiffen 1950a) as a special'
doi:10.1098/rspa.1960.0053 fatcat:qhmc7wtm4zbh5mzrtxg5rvlxjq