Abstract
Dense barium vapour (1019-1021 m-3) produced in a heatpipe oven is irradiated by a laser light pulse (4.6*108 W m-2, 300 ns, 30 pm) tuned to the resonant transition at lambda =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 mu m; 1.13 mu m; 2.55 mu m) in the barium vapour is measured. When the laser pulse is tuned out of resonance the ion density decreases resonantly whereas the population densities of the low-lying Ba I states do not. This resonant ionisation behaviour is interpreted by means of radiative processes.

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