Temperature dependence of the quenching of O(1S) by simple inorganic molecules

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Abstract
The quenching of metastable O(1S) atoms by H2 , O2 , CO, CO2 , N2O, and SF6 was studied in the temperature range 210–470 K. Very low concentrations of O(1S) atoms were generated in the pulsed vacuum ultraviolet (VUV) Lα photolyses of N2O and CO2 . The atoms were detected by their forbidden emission at around 557.7 nm, the intensity of which was enhanced by the formation of exciplexes in the presence of Ar. The quenching by H2 and SF6 is very inefficient and occurs without a significant activation energy. The rate constants for the quenching by CO and CO2 can be represented by activation energies near 10 kJ mol−1 but very different frequency factors. The collisions of O(1S) with O2 and N2O lead to different products which likely are formed with different activation energies. It is proposed that generally quenching of O(1S) proceeds by diabatic processes.