Dynamics of the emission spectrum of laser breakdown on the surface of water

An experimental investigation was made of the emission spectra of a laser plasma which appeared on the surface of distilled water and of aqueous solutions of NaCl and FeBr₂ during a time interval of 0.2–8 μs after the action of a YAG:Nd³⁺ laser pulse. The intensity of the continuous spectrum and the temperature of the plasma fell at a rate characterized by a time constant ~ 2 μs, whereas the intensity maximum in the line spectra of the elements depended on the energy of the relevant excited state, so that the kinetics of the emission spectrum obtained above the surface of water was basically similar to the kinetics of the radiation emitted by a plasma jet formed above the surface of a solid.