The study of VUV emissions of Ar*2 excimers using three-photon absorption laser-induced fluorescence

Abstract

The VUV emissions of the second continuum of argon at ∼130 nm were investigated for pressures ranging from 100 to 600 Torr after selectively populating the resonant atomic state of the 3p54s configuration of argon by using three-photon absorption laser-induced fluorescence. For brief and selective excitation conditions, a kinetic study was performed by analysing the VUV postluminescence decay of argon. This study clearly shows that only three-body collisions lead to the formation of the excimer Ar2(A1u). The three-body decay rate constant of the metastable state Ar4s[3/2]02 was measured for the first time under selective excitation (k′3 = (19.5 ± 2.1) Torr−2 s−1). The role of the first resonant and metastable states of argon in the formation of excimers responsible for the VUV emissions is discussed. A kinetic scheme showing the main reaction processes is proposed and compared with those already obtained with other rare gases.