Collisional deactivation of the isoelectronic15N+2Athinsp;2Pgr;ui(v=3) and CO+Athinsp;2Pgr;i(v=3 and 4) levels by helium atoms

摘要

An opticalndash;optical double resonance (OODR) technique is used to selectively populate rotational levels of the15N+2Athinsp;2Pgr;ui(v=3) state and monitor collision induced electronic transitions (CIET) to theXthinsp;2Sgr;+g(v=6 and 7) vibronic manifolds. The branching ratio from theA(v=3) state to theX(v=6 and 7) levels is determined experimentally and used in a phenomenological model based on past results. This ratio is used to determine the state specific collisional quenching rates from observed double exponential decay curves of theA(v=3) level. Similar results are obtained for CIET from the CO+Athinsp;2Pgr; (v=4) level to theXthinsp;2Sgr;+(v=12 and 13) levels. In this case, the branching ratio from theA(v=4) level to theX(v=12 and 13) levels is not as accurate as for the15N+2case, but the result agrees with the empirical model, and state specific quenching rates are also determined from double exponential decay curves. In addition, the deactivation rate is determined for the CO+A(v=3) level from its observed single exponential laser induced fluorescence curves. These new data for quenching of the CO+A(v=3 and 4) states continues the trend of increasing quenching cross sections with increasing vibrational quantum number observed in previously published values for theA(v=0, 1, and 2) levels. A comparison is also made between rotational relaxation within theA(v=4) state and the abovementioned electronic deactivation in CO+. These results show that CIET in CO+compares favorably to analogous experiments with its isoelectronic partners N+2and CN, including energy gap and Franckndash;Condon factor dependencies. The collider in all cases is helium.