Dielectric Constants of Imperfect Gases. III. Atomic Gases, Hydrogen, and Nitrogen

A modified cyclic-expansion method has been used to determine dielectric constants as a function of relative density with a precision of less than 1 ppm for He, Ne, Ar, Kr, H2, and N2 at 49°C and pressures below 150 atm, which with data at measured pressures below 7 atm determine the first and second dielectric virial coefficients, and can also be used to determine pressure second virial coefficients. Dielectric second virial coefficients are for all six gases less than values predicted by present theories of fluctuations and pair polarizabilities, an effect believed to result from overlap interactions at short range. The low-density values of the Clausius—Mossotti function are in good agreement with other recent determinations.