Mechanism of luminescence of the surfaces of some materials under the action of laser radiation

An experimental investigation was made of visible luminescence generated by the action of laser radiation (10.6 and 1.06 μ) pulses on NaCl and graphite targets. It was found that the air above the target became conducting before such luminescence was emitted. Admission of helium into the chamber containing a target reduced the intensity and the trailing edge duration of the luminescence pulses. The observed effect was attributed to the emission of charged particles and to the adsorption of a gas on the irradiated surface.