Quenching of metastable Ar, Kr, and Xe atoms by oxygen-containing compounds: A resonance fluorescence study of reaction products

Quenching of electronically excited Ar, Kr, and Xe(3P0,2) atoms by diatomic and triatomic oxygen-containing compounds has been studied by atomic resonance fluorescence in a discharge-flow system at room temperature. Absolute branching ratios for molecular fragmentation in the quenching reactions have been obtained, showing that this channel is dominant in many cases. While single R–O bond cleavage is usually the favored process, cleavage of both bonds of H2O occurs in nearly 50% of quenching collisions with Ar*, and evidence is obtained for analogous atomization of NO2 and SO2 by Ar*. Emission by electronically excited fragment species has been found to be mostly weak; thus, dissociative excitation is a minor channel except for the reactions of Ar* with N2O and H2O.