Inelastic cross-sections and natural lifetimes for the 6²D_{3/2, 5/2} and 8²S_1/2 states of Rb

The results of an experimental study of population dynamics following excitation of 6²D_{5/2, 3/2} and 8²S_1/2 states of rubidium are reported. Excitation transfer and quenching cross-sections in collisions with ground state rubidium atoms, and natural lifetimes have been measured. The experiment was performed in a vapour cell, using pulsed two-photon excitation and photon counting detection. The analysis of time dependent signals was based on a rate equation model in which transitions induced by thermal radiation have been accounted for. The measurements yielded following results: (1) 6²D state J-mixing cross-section: σ^Rb-Rb_{6D5/2→6D3/2} = 9.2(2.1) × 10^-14 cm²; (2) cross-sections for 8²S → 6²D excitation transfer process: σ^Rb-Rb_8S→6D = 3.4(1.2) × 10^-14 cm²; (3) quenching cross-sections: σ^Rb-Rb_{q, 8S} = 12.8(3.4) × 10^-14 cm^2, σ^Rb-Rb_{q, 6D3/2} = 22.8(2.9) × 10^-14 cm^2, σ^Rb-Rb_{q, 6D5/2} = 14.1(5.7) × 10^-14 cm^2; (4) radiative lifetimes: τ_8S = 161(3) ns, τ_6D3/2 = 256(4) ns, τ_6D5/2 = 249(5) ns.