title: Ultra-fast charge migration competes with proton transfer in the early chemistry of H2O˙.
abstract: Oxidation by the ultra-short lived radical cation of water, H2O˙+, can potentially take place at the interface of water and numerous heterogeneous systems involved in radiation therapy, energy and environmental industries. The oxidation processes induced by H2O˙+can be mimicked in highly concentrated solutions where the nearest neighbors of H2O˙+may be molecules other than water. The reactivity of H2O˙+and D2O˙+is probed in hydrogenated and deuterated sulfuric acid solutions of various concentrations. The oxidized solute, sulfate radical, is observed at 7 ps and remarkably higher yields are found in deuterated solutions. The isotopic effects reveal the competition between two ultrafast reactions: proton transfer toward H2O (D2O) and electron transfer from HSO4-to H2O˙+(D2O˙+). Density functional theory simulations decipher the electron transfer mechanism: it proceeds via sub-femtosecond charge migration and is not affected by isotopic substitution. This work definitively demonstrates why direct oxidation triggered by H2O˙+can be competitive with proton transfer.
authors.affiliation: Laboratoire de Chimie Physique, CNRS-Université Pari-Sud, Bat. 349, 91405, Orsay, France. mehran.mostafavi@u-psud.fr.
authors.forename: Furong
authors.initials: F
authors.lastname: Wang
authors.affiliation: Laboratoire de Chimie Physique, CNRS-Université Pari-Sud, Bat. 349, 91405, Orsay, France. mehran.mostafavi@u-psud.fr.
authors.forename: Uli
authors.initials: U
authors.lastname: Schmidhammer
authors.affiliation: Laboratoire de Chimie Physique, CNRS-Université Pari-Sud, Bat. 349, 91405, Orsay, France. mehran.mostafavi@u-psud.fr.
authors.forename: Aurélien
authors.initials: A
authors.lastname: de La Lande
authors.affiliation: Laboratoire de Chimie Physique, CNRS-Université Pari-Sud, Bat. 349, 91405, Orsay, France. mehran.mostafavi@u-psud.fr.
authors.forename: Mehran
authors.identifier: http://orcid.org/0000-0002-4510-8272
authors.initials: M
authors.lastname: Mostafavi