SIMULTANEOUS MEASUREMENT OF DIELECTRIC-CONSTANT AND REFRACTIVE-INDEX OF SF6 AND CO2 AS A FUNCTION OF PRESSURE

Static dielectric constant epsilon and refractive index n have been me asured simultaneously over a large pressure range (approximate to 23 M Pa). The measurements are carried out at temperatures in the supercrit ical region both for SF6 and CO2. From these static measurements, we d etermined the coefficients gamma(1), gamma(2),..., related to the line ar, quadratic,..., density dependence. It is shown that the meaningful physical coefficients gamma(1), are related to the integrated absorpt ion by means of the Kramers-Kronig relation. For SF6, the results are compared with the earlier dielectric and optical results. For CO2, the binary coefficients gamma(2) are in good agreement with the static an d the absorption results. Furthermore, our results together with the a ccurate existing integrated absorption data demonstrate the temperatur e dependence of the gamma(2) component. (C) 1997 American Institute of Physics.