We have developed a novel dischargendash;flow technique for studying the quenching of N2(Xthinsp;1Sgr;+g,vlsquo;ge;5) and N2(Bthinsp;3Pgr;g) by a variety of molecules. The technique involves adding small number densities of N2(Athinsp;3Sgr;+u) to a flow of N2(X,v) producing, thereby, N2(B). By comparing N2(B) fluorescence intensities generated when a quencher is added to the N2(X,v) flow 2ndash;3 ms before N2(A) addition with intensities observed after the N2(X,v) and quencher have been mixed for times of 10ndash;30 ms, we can separate the effects of N2(B) fluorescence quenching from effects of N2(X,v) quenching. Our results indicate that CH4, CO2, CO, O2, and N2O quench N2(B) at rates approaching gas kinetic while H2, N2, SF6, and CF4are about ten times slower. Rate coefficients for N2(X,vlsquo;ge;5) quenching by H2and N2are on the order of 10minus;15cm3thinsp;moleculeminus;1thinsp;sminus;1, those for CO2, CH4, and CF4roughly an order of magnitude faster, and CO and N2O yet another order of magnitude faster.
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