Anisotropic density fluctuations in argon at different densities: Far infrared measurements and molecular dynamic calculations

Abstract

From measurements of the pure rotational lines of a linear probe molecule dissolved in a simple fluid one can deduce the power spectra of the anisotropic density fluctuations of /=1 and /=2 symmetry of the fluid. The power spectra thus obtained for argon at various densities are compared with the results of molecular dynamics calculations and with the approximate power spectra which can be calculated starting from neutron-scattering data. The density dependence of the high frequency components of the /=1 power spectrum and of the zero frequency component of the /=2 power spectrum give a strong characteristic of the dense fluid.