Direct Flow Measurement of O2(b1Σg+) Quenching Rates

Abstract

A relaxation method is developed which permits a direct measurement of ${\mathrm{O}}_2{\mathrm{(b}}^1{\Sigma }_g^{+})$ quenching rate constants. An Al wire spiral is used to selectively quench ${\mathrm{O}}_2{(}^1\mathrm{\Sigma )}$ which is normally present in discharged oxygen as a steady‐state intermediate. The characteristic time for the reestablishment of the ${\mathrm{O}}_2{(}^1\mathrm{\Sigma )}$ steady state is used to determine wall and bimolecular quenching rates. With this method, absolute rate constants are obtained from relative intensity measurements of the ${\mathrm{O}}_2{(}^1\mathrm{\Sigma )}$ emission at 7619 Å. The rate constant for quenching by H₂O is found to be 4.0 ± 0.6 × 10⁻¹² cc sec⁻¹. Rate constants for a number of other quenchers are reported.