Energy pooling and associative ionization following laser excitation of mercury vapor

Abstract

Laser excitation of the Hg(63P1←61S0) transition at 253.7 nm permits selective population of Hg(63P1). Subsequent quenching by N2 yields Hg(63P0). Observation of emission spectra and temporal profiles of emission features following laser excitation of Hg/Ar mixtures reveals that energy pooling of two Hg(63P1) yields Hg(61S0) plus mercury in the 93S1,73D3,71D2, and 81S0 states, all of which lie no more than 0.6 eV below 2×E[Hg(63P1)]. Collisions of Hg(63P1) with Hg(63P0) are dominated by associative ionization to yield Hg+2, dissociative recombination of which produces a long-lived tail in the atomic emission signals. This work confirms the high efficiency of associative ionization involving atoms in the 63P1 and 63P0 states. The atomic states observed following subsequent dissociative recombination agree well with those reported previously.