Interaction of ultraviolet radiation with diatomic and triatomic metal halide vapors is discussed. Patterns observed in ultraviolet absorption cross sections are noted. Measurements of quantum efficiency of fluorescence excited by photodissociation (QE = fluorescence photons out/ultraviolet photons in) are described. Results and their implications for 205 ± 15-nm deuterium, 213.9-nm-Zn resonance and deuterium VUV excitation are discussed. Applications of photodissociation in photodissociation lasers, electric discharge lamps, and collisional processes such as measurement of reactive and quenching cross sections are summarized.