Photoionization and Absorption Cross Sections and Fluorescence of CF4

Abstract

Absorption and photoionization cross sections for CF4 were measured in the 600-to-1000-Å region using a 1-m Seya-type scanning ultraviolet monochromator with a resolution of 0.7 Å. The Hopfield continuum of He2 was used as the light source. The cross sections obtained show that from 600 to 1000 Å the absorption is continuous with broad maxima at 910 Å, 780 Å, and 660 Å, and broad minima at 830 Å and 760 Å. The appearance potential of ions was located at 15.56±0.01 eV (796.7 Å). Photoionization efficiencies were computed and the results indicate that processes other than ionization, such as dissociation or excitation to higher electronic states, are appreciable. Maximum fluorescent emission from the irradiated gas was observed to occur when the wavelength of the incident radiation was 905 Å.