Spectral absorption of solid CO2 from the ultraviolet to the far-infrared

The absorption coefficient k of solid CO2 has been measured in the wavelength range from lambda=170 nm in the ultraviolet to 333 mu m in the far-infrared, except for the strong bands where k>5000 m(-1). This was accomplished by measuring the transmission of clear samples of solid CO2 grown in equilibrium at 150 K in a chamber whose path length was set between 1.6 and 108 mm. The transmission was measured using both a grating monochromator (lambda<2 mu m) and a Fourier transform spectrometer (lambda>1.2 mu m). Resolving powers (lambda/Delta lambda) of greater than 5000 were required to measure the narrowest absorption lines in the infrared. The far-infrared lattice-absorption lines are very broad and relatively weak at 150 K compared to lower temperatures. The absorption coefficients in the weakly absorbing "windows" between the strong infrared absorption bands are less than or equal to 1 m(-1), the minimum level which could be measured accurately in this experiment. No absorption was measurable from the near ultraviolet, throughout the visible, to 1.4 mu m except for a few narrow lines at lambda>1 mu m. (C) 1997 COSPAR. Published by Elsevier Science Ltd.