Collisional and radiative processes in a laser-pumped barium vapour

Abstract
Dense barium vapour (1019-1021 m-3) produced in a heat-pipe oven is irradiated by pulsed laser light tuned to the Ba I, 6s2 1S0-6s6p 1P10, resonance transition at 553.55 nm. The transient population densities of various Ba I and Ba II states are measured and time-resolved by means of the hook method. Simultaneously, the IR forward scattering (1.5, 1.13, 2.55 mu m) in the barium vapour is measured. Emphasis is laid on the investigation and the interpretation of the IR emission, the 'anomalous' 6p 3P20 level overpopulation, and of processes which are responsible for the initiation of ionisation. In addition, the radial diffusion of excitation and ionisation energy in a barium vapour pumped with a focused laser pulse is investigated, as well as the energy transfer in a Ba-Sr vapour.