Kinetic Theory of Molecular Gases II: Calculation of Time Dependent Correlation Functions

Kinetic model equations, based on the Waldmann–Snider equation and valid over a wide range of wavelength and frequency, are applied to the study of time dependent correlation functions in a dilute molecular gas. In particular, the density autocorrelation function is calculated and its double Fourier transform compared with the polarized Rayleigh–Brillouin light scattering. Similarly, the tensor polarization autocorrelation function is studied and its spectrum compared to the depolarized Rayleigh light scattering. Thus, both scalar and tensorial phenomena are studied from a unified viewpoint. Furthermore, the asymptotic form of the theory is used to study in detail the behavior of the tensor polarization correlation function in the pressure broadening region.