ABSTRACT
This chapter presents the results of measurements of the complex index of refraction of commercially available solid carbon dioxide in the wavelength range 0.35-1.0 µm. Unlike the thin film techniques previously employed to determine the real portion of the index [1,2], the present method of measurement is relatively simple and obtains the real and imaginary portions. Our technique involves the determination of the Brewster angle on bulk solid CO2; the absorption was determined from direct transmission measurements on thin sections of solid CO2. A Perkin-Elmer 13U spectograph was modified to permit polarization measurements between angles of incidence of 23° and 90° over a 56.5 cm path length [3]. The ultraviolet (UV) and visible measurements were made with a Type 1P21 photomultiplier, and the infrared (IR) measurements were made with a Type 7102 photomultiplier. Narrowband interference filters were used in conjunction with the monochromator to eliminate errors caused by scattered light at wavelengths other than those under observation. Measurements were made at wavelengths of 0.35, 0.46, 0.56, 0.70, 0.97, and 1.0 µm.
