ABSORPTION CROSS SECTION OF GASEOUS ACETYLENE AT 85 K IN THE WAVELENGTH RANGE 110-155 nm

Absorption spectra and absorption cross sections of gaseous acetylene, C 2 H 2 , at 298 and 85 K were measured in the wavelength range 110–155 nm with a slit–jet system coupled to a synchrotron as a source of vacuum ultraviolet light. Using published spectral parameters of C 2 H 2 , we simulated the absorption profile for the Rydberg transition to state 4 R 0 in the range 124.6–125.1 nm, according to which the temperature of the jet-expanded sample at stagnation pressure 200 Torr is 85 ± 5 K. Our cross sections of C 2 H 2 are applicable for determining properties sensitive to temperature for diagnostic work on Saturn and Titan.