Index of refraction measurement of uranium hexafluoride vapor at 632.8 nanometers and 457.9 nanometers

The index of refraction of uranium hexafluoride (UF₆) vapor was measured at 632.8 nanometers and 457.9 nanometers using a Michelson interferometer. The refractive index was determined from the fringe shifts of the interference pattern as the UF₆ gas was fed into the evacuated test cell of the interferometer. Measurements were made at room temperature and at pressures ranging from 0 to 90 torr. At a confidence level of 90%, the resulting equations for the index of refraction of UF₆ vapor at the two colors are:

(n - 1) = (5.268 ± 0.010) x 10^-4 P (torr)/T (K) at 632.8 nm T (K)

and

(n - 1) = (5.414 ± 0.014) x 10^-4 P (torr)/T (K) at 457.9 nm.

A nonideality correction factor has been reported for UF₆. For the temperature and pressure range covered in this experiment, the correction factor was negligible; but for extrapolation of the data to higher pressures and temperatures, the correction factor should be included. The resulting equations are:

(n - 1) = (5.233 ± 0.010) x 10^-4 P(1 + AP)/T (K) at 632.8 nm

and

(n - 1) = (5.381 ± 0.014) x 10^-4 P(1 + AP)/T (K) 457.9 nm.

where

A(torr^-1) = 1622.1/T³ (K) .