RATE COEFFICIENTS FOR THE REACTION AND RELAXATION OF VIBRATIONALLY EXCITED H2O(VERTICAL-BAR-04](-)) WITH H-ATOMS AND H2O

Rate coefficients are reported for the removal of H2O in its \04](-) v ibrational state in collisions with H atoms and with H2O. Pulses of tu nable infrared radiation at 719 nm excite H2O molecules in gas mixture s in which the concentrations of both H2O and H atoms are known. OH ra dicals formed in the reaction between H and H2O(\04](-)) are observed by laser-induced fluorescence and the time delay between pulses from t he infrared ''pump'' and ultraviolet ''probe'' lasers is varied to pro vide 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.