Rate coefficients for the reaction and relaxation of vibrationally excited H2O(|04⟩-) with H atoms and H2O

Rate coefficients are reported for the removal of H2O in its \04](-) vibrational state in collisions with H atoms and with H2O. Pulses of tunable infrared radiation at 719 nm excite H2O molecules in gas mixtures in which the concentrations of both H2O and H atoms are known. OH radicals formed in the reaction between H and H2O(\04](-)) are observed by laser-induced fluorescence and the time delay between pulses from the infrared "pump" and ultraviolet "probe" lasers is varied to provide kinetic data. Rate coefficients have been determined for (i) the self-relaxation of H2O(\04](-)) by other water molecules, k(2)=(2.2+/-0.2)x10(-10) cm(3) molecule(-1) s(-1) and (ii) the removal of H2O(\04](-)) by H atoms, k(2)=(4.9(5)+/-0.6)x10(-10) cm(3) molecule(-1) s(-1). (C) 1998 American Institute of Physics.