WATER FORMATION THROUGH A QUANTUM TUNNELING SURFACE REACTION, OH + H2, AT 10 K

Atom Tunneling in the Water Formation Reaction H2 + OH → H2O + H on an Ice Surface

OH radicals play a key role as an intermediate in the water formation chemistry of the interstellar medium. For example the reaction of OH radicals with H2 molecules is among the final steps in the astrochemical reaction network starting from O, O2, and O3. Experimentally it was shown that even at 10 K this reaction occurs on ice surfaces. As the reaction has a high activation energy only atom ...

Title Signatures of Quantum - Tunneling Diffusion of Hydrogen Atoms on Water Ice at 10 K

Signatures of Quantum-Tunneling Diffusion of Hydrogen Atoms on Water Ice at 10 K.

Reported here is the first observation of the tunneling surface diffusion of a hydrogen (H) atom on water ice. Photostimulated desorption and resonance-enhanced multiphoton ionization methods were used to determine the diffusion rates at 10 K on amorphous solid water and polycrystalline ice. H-atom diffusion on polycrystalline ice was 2 orders of magnitude faster than that of deuterium atoms, i...

The cumulative reaction probability for the H2 1 OH reaction

The cumulative reaction probability @CRP or N(E)] for the four-atom reaction, H21OH→H 1H2O is calculated using one of the formulations of Miller, Schwartz, and Tromp @J. Chem. Phys. 79, 4889 ~1983!# and the transition state wave packet ~TSWP! approach of Zhang and Light @J. Chem. Phys. 104, 6184 ~1996!#. It is shown that locating the dividing surface of the flux operator in the transition state...

Relevance of the H2 + O reaction pathway for the surface formation of interstellar water

The formation of interstellar water is commonly accepted to occur on the surfaces of icy dust grains in dark molecular clouds at low temperatures (10–20 K), involving hydrogenation reactions of oxygen allotropes. As a result of the large abundances of molecular hydrogen and atomic oxygen in these regions, the reaction H2 + O has been proposed to contribute significantly to the formation of wate...