Vacuum ultraviolet fluorescence from photodissociation fragments of CO and CO2

摘要

The vacuum ultraviolet fluorescence from photofragments of CO and CO2has been studied and the cross sections for the production of fluorescence have been measured. The fragments were produced by interactions of the gases with synchrotron radiation in the wavelength region lgr;lgr;175ndash;800 Aring;. The dependence of the fluorescence intensity on gas pressure was studied and at high pressure additional fluorescence induced by photoelectrons was observed. Discrete features were observed in CO in the primary photon wavelength region lgr;lgr;570ndash;610 Aring;. Similar features were observed in CO2in the lgr;lgr;690ndash;800 Aring; region corresponding to Rydberg states converging to the CO+2(Athinsp;2Pgr;) and CO+2(Bthinsp;2Sgr;+) states. The observed structure results from interactions of Rydberg states with dissociation continua. At shorter primary photon wavelengths the cross sections for the production of fluorescence from photofragments of CO decrease monotonically from 3.6 Mb at lgr;480 Aring; to 1.2 Mb at lgr;180 Aring;. In contrast with this, two broad bands were observed in the fluorescence from photofragments of CO2with peak cross sections of 0.73 Mb at lgr;230 Aring;. The photodissociation and dissociative ionization processes that produce the observed results are discussed.