Abstract: A gaseous laser medium is photodissociated into an upper laser state by vacuum ultraviolet light from an electrically excited noble gas mixed with the laser medium. A gaseous laser medium, such as cyanogen bromide, is preferably resonantly excited by photodissociation by such vacuum ultraviolet light. CN particles in the B state undergo laser transition to the X state, producing radiation at about 4000A. Alternatively or additionally, a gaseous laser medium is excited to produce molecules, such as halogen molecules, particularly Br.sub.2, in an upper laser state whence they undergo transition by laser action to a weakly bound lower laser state that is rapidly depopulated.