Experimental investigations of reactions of hot hydrogen atoms with molecular hydrogen and water

The state-to-state integral rate constants were measured for the three reactions: (1) D + H2(vj) → HD(v' = 0,1,2;j) + H at Erel = 1.4 and 0.8 eV and (2) H + D2 → HD(v' = 1,j') + D at Erel = 2.2 and 2.5 eV, and (3) H + D2O → HD(v',j'), + OD at Erel = 2.7 eV. The reagents were either in the ground state, (v = 0,j), or for the D + H2 work prepared in the first excited vibrational state, (v = 1, j = 1), by stimulated Raman pumping. Translationally hot D(H) atoms were generated by UV photolysis of D(H)I. Resonance-enhanced multiphoton ionization and time-of-flight mass spectrometry were employed to detect the nascent HD product in a quantum-state-specific manner. For the reaction D + H2 we find that vibrational excitation of the H2 reagent results in: (1) substantial HD rotational excitation for each product vibrational state, (2) a open-quotes heatingclose quotes of the vibrational product state distribution, and (3) almost no change in the total rate into HD(v' = 0,1,2;j'). The experimental results are consistent with a model in which internal energy of the reagents is conserved. Good to excellent agreement is found between the experiment and recent quantum-mechanical (QM) scattering calculations. The reaction H + D2 → HD(v' = 1,j') + D was studied at high collision energies. These experiments provide data that will be useful for determining the importance of the Jahn-Teller effect in reactive scattering systems and to the development of theoretical techniques in which the ground and first excited electronic surfaces are included in QM calculations. For the reaction H + D2O, approximately 35% (12% in vibration, 23% in rotation) of the available energy is partitioned into the internal modes of the HD product