Lifetimes and quenching of B2Σ+ PO by atmospheric gases

Pulsed laser excited fluorescence in the B 2Σ+ ← X 2π system of gas phase PO was used to measure the lifetime for v’=0 of the B state. Rotationally resolved measurements for a few selected J’ levels, at Ar or He carrier gas pressures of ∼2 Torr, reveal no dependence of the lifetime on the rotational level excited. Earlier measurements of relative fluorescence intensities in the v’=0 vibrational progression were reinterpreted to extract the dependence of the electronic transition moment on internuclear distance. Using this transition moment, no lifetime dependence on rotational level is to be expected, even at low pressures. Rate constants for quenching of the B state PO by N2, O2, CO2, and H2O, and upper limits thereof for He and Ar are reported. O2 was found to react with ground state PO. A crude measurement of the rate constant was performed. The result is compared to two other known measurements. The rate constant is in excellent agreement with the previous measurement, but in poor agreement with that ...