FREQUENCY-DEPENDENCE OF 2ND REFRACTIVITY VIRIAL-COEFFICIENTS OF SMALLMOLECULES 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 ro om temperature interferometric measurements are carried out between 32 5 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 simp le theoretical considerations, showing mostly fair agreement between t he calculated and measured dispersion of the second refractivity viria l coefficients.