Generation of coherent ultraviolet radiation in the 330 nm region by multiphoton excitation of sodium vapor

We report the observation of coherent uv emission at 330.2±0.5 nm when sodium vapor in a heatpipe is irradiated with a pulsed visible dye laser with output wavelength in the 570–595 nm region. It is found that intense uv emission can be produced from Na atoms as well as from Na₂ molecules. The excitation functions and their dependence on vapor density and laser power density are presented and the mechanisms for producing the emission are discussed.