Product channels of the reactions of Rb(62P) with H2, CH4 and C2H6

Abstract

Branching fractions for product channels of the reactions of Rb(62P) with H2, CH4 and C2H6 involving energy transfer and chemical transformation have been measured using time-resolved pulsed laser techniques. Removal of Rb(62P) atoms was monitored using laser induced fluorescence (LIF) measurements. The RbH product was detected using LIF of the A-X transition in the 500–530nm spectral range. Pump-probe measurements indicated a collisional loss of rubidium atoms due to the reactions of Rb(62P) with H2 and C2H6 with branching fractions γH2ch=0.21±0.03 and γC2H6ch=0.10±0.03, respectively. The measurements for Rb(62P) + CH4 did not provide conclusive evidence for a reactive loss channel. We detected RbH (v=0, 1 and 2) produced from Rb(62P) in the presence of H2. Surprisingly, the RbH product was not detected with CH4 or C2H6, despite the fact that high-level ab initio calculations show the existence of favorable pathways for RbH formation. The branching fractions for the energy transfer product channels were found to be γH2rel=0.79±0.05, γC2H6rel=0.92±0.05 and γCH4rel=0.98±0.05 for H2, CH4 and C2H6, respectively. The undetectable loss of Rb via the reaction with methane suggests that CH4 may be the more stable diluting agent for use in the diode pumped Rb vapor laser system.