Light scattering orientational memory functions for fluid N₂ at moderate densities

Abstract

Room temperature rotational Raman spectra of N₂ in the 56–135 amagat density range are employed to test the memory function approach to rotational dynamics. Memory functions of order one and two in the Mori hierarchy are derived from the spectra and compared with the corresponding calculated free rotor memory functions. It is found that the free rotor memory function multiplied by a decaying function approximately reproduces the experimental curves, the degree of approximation being sensibly better for the second order memory function. Exponentially decaying functions are required to reproduce the long time behaviour of both experimental memory functions. At short times a gaussian decay is found to be more adequate for the first order memory function. Decay parameter values are discussed and compared with available theories.

Work partially supported by C.N.R.

Work partially supported by C.N.R.

Notes

Work partially supported by C.N.R.