Collisional excitation transfer and quenching inRb(5P)-methane mixtures

Abstract

We have examined fine-structure mixing between the rubidium 5 2 P 3/2 and 5 2 P 1/2 states along with quenching of these states due to collisions with methane gas. Measurements are carried out using ultrafast laser pulse excitation to populate one of the Rb 5 2 P states, with the fluorescence produced through collisional excitation transfer observed using time-correlated single-photon counting. Fine-structure mixing rates and quenching rates are determined by the time dependence of this fluorescence. As Rb(5 2 P ) collisional excitation transfer is relatively fast in methane gas, measurements were performed at methane pressures of 2.5 − 25 Torr, resulting in a collisional transfer cross section (5 2 P 3/2 → 5 2 P 1/2 ) of (4.23 ± 0.13) × 10 −15 cm 2 . Quenching rates were found to be much slower and were performed over methane pressures of 50 − 4000 Torr, resulting in a quenching cross section of (7.52 ± 0.10) × 10 −19 cm 2 . These results represent a significant increase in precision compared to previous work, and also resolve a discrepancy in previous quenching measurements. arXiv:1812.09466v1 [physics.atom-ph]

Theoretical study of the control of absorption, transparency, and amplification in a microwave- and RF-driven four-level (Δ + ∇)-type closed-contour interaction system

“…Actually, this decision is taken due to the fact that the values of any non-radiative decay rates are very small compared to the spontaneous decay rates [42]. Nevertheless, a further investigation of the various collisional decoherence effects on the coherence phenomena can be done by considering the decohering aspects due to the different collisional quench rate coefficients of Rb atoms in the presence of various buffer gases in a Rb vapour cell [43,44]. In our numerical simulation, all the parameters are scaled with the spontaneous decay rate (γ) between the excited state to the ground state of the atomic system under consideration for simplicity.…”