Laser fluorescence experiments with a pulsed dye laser in an argon plasma

Abstract

We have carried out laser-induced fluorescence experiments in the argon plasma of a hollow cathode arc (HCA) using a pulsed-dye laser. The pumping line was the 611.5 nm transition between the metastable 3 d′ 2 G 9 2 and the 4 p′ 2 F 7 2 level in the argon-ion system (′ refers to the 1 D core of the two times ionized argon atom). From the measured fluorescence signal of the 4 p′ 2 F 7 2 upper level, we are able to determine the deexcitation coefficient [(2.5±1.0) 10 -14 m 3 sec -1] and the density of the 3 d′ 2 G 9 2 metastable level (1.5×10 15−1.25×10 16 m -3). The 3 d′ 2 G metastable doublet is a serious candidate for excitation of the 4 p upper laser levels and may partly be responsible for the 4 s−4 p inversion which causes the argon-ion laser oscillation.