Investigation of the collisional behaviour of Ba[6s5d( 3D 1,2,3)] generated following pulsed dye-laser excitation at [formula omitted] by spectroscopic marker methods in the presence of krypton part II

Abstract

We present a kinetic investigation of Ba[6s5d( 3D J )], 1.151 eV above the 6s 1( 1S 0) ground state in the presence of krypton gas following pulsed dye-laser excitation of atomic barium vapour at elevated temperatures at λ = 553.5 nm { Ba[6 s6 p( 1 P 1)] ← Ba[6 s 2( 1 S 0)]} . The 3D J state is neither directly accessible by laser excitation nor is it possible to monitor this state by emission at λ = 1106.9 nm { Ba[6 s5 d( 3 D 1)] → Ba[6 s 2( 1 S 0)]} . Thus, in the ‘long time-domain’, Ba( 3D J ) h been monitored by the spectroscopic marker transitions at λ = 791.1 nm { Ba[6 s6 p( 3 P 1)] → Ba[6 s 2( 1 S 0)]} and λ = 553.5 nm { Ba[6 s6 p( 1 P 1)] → Ba[6 s 2( 1 S 0)]} , the former from collisional excitation with the buffer gas and atomic barium in its electronic ground state and the latter from energy pooling accompanying Ba( 3 D J) + Ba( 3 D J) self-annihilation. Measurement of the first-order rate coefficients for the exponential decay of these two emitting states were characterised and where the decay coefficients for the profiles at λ = 791.1 and 553.5 nm were found to be in the ratio 1:2, respectively, in this long-time regime on the basis of collisional excitation and energy pooling of Ba( 3D J ). The variation of the integrated atomic emission intensities, coupled with optical sensitivity calibrations, are presented for the range of densities of Kr employed. These rate measurements are used to describe quantitatively the collisional and diffusional processes undergone by Ba( 3D J ) with both Kr and with ground state Ba.