Collisional quenching of OH(A (2)Sigma(+), upsilon '=0) by H2O between 211and 294 K and the development of a unified model for quenching

The cross-section for electronic quenching of OH(A (2)Sigma(+), upsilon' = 0) by H2O was found to increase from 82 +/- 8 Angstrom(2) at 294 K to 119 /- 11 Angstrom(2) at 211 K. Both OH(A (2)Sigma(+)) and H2O display relative ly large dipole moments, and a 'harpooned' mechanism occurring on a Lennard -Jones potential energy surface modified to include dipole moment effects w as found to reproduce the observed temperature dependence of the cross-sect ions in the range 211-2300 K. The model, which is general, will enable corr ections for the effects of quenching on laser-induced fluorescence signals to be made with a high degree of confidence in combustion and atmospheric m edia. (C) 1999 Elsevier Science B.V. All rights reserved.