FREQUENCY-DEPENDENCE OF 2ND REFRACTIVITY VIRIAL-COEFFICIENTS OF SMALL MOLECULES BETWEEN 325 NM AND 633 NM

The dispersion of the second refractivity virial coefficient B-R(omega, T) is determined for the gases Ar, Kr, Xe, O-2, N2O, CO2, NH3, CH4, C2H4, C2H6, C3H6, and cyclo-C3H6 relative to a given fixed value B-R((0))(omega, T) using low-pressure refractive index measurements. The room temperature interferometric measurements are carried out between 325 nm and 633 nm, using four fixed wavelengths simultaneously, in order to obtain precise information of the pressure-dependent dispersion of the refractive index. The experimental results are compared with simple theoretical considerations, showing mostly fair agreement between the calculated and measured dispersion of the second refractivity virial coefficients.