Photodissociation of CO: Partial cross sections for neutral dissociative excitation

Dispersed vacuum-ultraviolet fluorescence from neutral dissociation fragments in the wavelength range from 100-200 nm has been measured after photodissociation of CO as a function of the exciting photon energy between 18.5 and 29 eV. The decay channels of neutral dissociative excitation of the formed CO Rydberg states converging to the CO+ D and C states have been analysed. The vibrationally excited levels of the R(D)(ns) and R(D)((n + 1)s) Rydberg states preferentially dissociate into the fragments C I(2s(2)2p(n - 1)d/ns (2S+1)L(J))+ O I(2s(2)2p(4 2S+1)L(J)). Relative cross sections for the observed lines of C I and O I have been obtained. For the lines at 193, 167.5 and 156 nm estimations for absolute cross sections are presented. Evidence for superexcited states has been found in the exciting photon energy range between 24 and 27.5 eV.