Direct laser excitation and quenching of the 4s state of sodium

Abstract

The second excited state 4S of atomic sodium has been directly reached by two-photon absorption with a YAG laser (10642 Å) and a tunable dye laser (6116 Å). Its observation is made through the cascade 3P−3S fluorescence light. The absolute quenching cross sections of the 4S state by nitrogen and hydrogen molecules are determined and compared to relative measurements made in beam experiments.