Abstract
The results of an experimental study of population dynamics following excitation of 6(2)D(5/2,3/2) and 8(2)S(1/2) states of rubidium are reported. Excitation transfer and quenching cross-sections ill 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) 6(2)D state J-mixing cross-section: sigma(6D5/2-->6D3/2)(Rb-Rb) = 9.2(2.1) x 10(-14) cm(2); (2) cross-sections for 8(2)S-->6(2)D excitation transfer process: sigma(8S-->6D)(Rb-Rb) = 3.4(1.2) x 10(-14) cm(2); quenching cross-sections; sigma(q,8S)(Rb-Rb) = 12.8(3.4) x 10(-14) cm(2), sigma(q,6D3/2)(Rb-Rb) = 22.8(2.9) x 10(-14) cm(2), sigma(q,6D5/2)(Rb-Rb) = 14.1(5.7) x 10(-14) cm(2); (4) radiative lifetimes: tau(8S) = 161(3) ns,tau(6D3/2) = 256(4) ns, tau(6D5/2) = 249(5) ns.