Fluorescence from photoexcitation of C2H2 at 50-106 nm

The photoabsorption and fluorescence cross sections of C2H2 were measured in the 50-106 nm region using synchrotron radiation as a light source. Fluorescence observed at several excitation wavelengths was dispersed to identify the fluorescing species that are excited C2H, C2, CH, H, and possibly C2H2. The photodissociation process of C2H2 leading to the formation of fluorescing species is discussed. The C2 (C-A) emission observed at 92.3 and 95.5 nm is produced by the molecular elimination process associated with superexcited state(s). Fluorescence spectra from the two-photon excitation of C2H2 at 157.5 and 193 nm were also observed and compared with those of single-photon excitation at the equivalent excitation energies.