Energy transfer studies on N2(X 1Σ+g,v) and N2(B 3Πg)

Abstract

We have developed a novel discharge–flow technique for studying the quenching of N2(X 1Σ+g,v″≥5) and N2(B 3Πg) by a variety of molecules. The technique involves adding small number densities of N2(A 3Σ+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 2–3 ms before N2(A) addition with intensities observed after the N2(X,v) and quencher have been mixed for times of 10–30 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 CF4 are about ten times slower. Rate coefficients for N2(X,v″≥5) quenching by H2 and N2 are on the order of 10−15 cm3 molecule−1 s−1, those for CO2, CH4, and CF4 roughly an order of magnitude faster, and CO and N2O yet another order of magnitude faster.