TEMPERATURE-DEPENDENCE OF THE ULTRAVIOLET-ABSORPTION CROSS-SECTION OF CF3I

The ultraviolet absorption cross section of CF,I has been measured in the gas phase over the wavelength range 160-240 nm for temperatures 240, 295 and 355 K and over the wavelength range 240-350 nm for temperatures ranging from 218 to 333 K. Two intense and sharp absorption bands centered at about 160 and 171 nm and a broad and relatively strong band centered at about 267.5 nm were observed. The absorption band centered at 171 nm shows significant vibrational structure. The cross sections, at absorption peaks, between 160 and 175 nm, increased by increasing temperature. At the near-UV maximum of 267.5 nm, the absorption increased with decreasing temperature, but decreased at the lowest temperature. At wavelengths greater than about 280 nm, the absorption cross section decreased with decreasing temperature. The absorption cross sections were found to all fit a triple Gaussian expression for lambda > 250 nm.