title: HCl adsorption on ice at low temperature: a combined X-ray absorption, photoemission and infrared study.
abstract: The reaction of HCl on water ice provides a simple case for understanding dissociation and proton transfer in this non-optimal, incomplete solvation environment, playing a central role in atmospheric chemistry. This reaction has been repeatedly reported as thermally dependent, whereas the theoretical models predict a spontaneous dissociation. We examine the adsorption of HCl on ice at low temperature (50 K and 90 K) via a combination of near-edge X-ray absorption spectroscopy (NEXAFS) at the chlorine L-edge, photoemission (XPS and UPS), and reflection-adsorption infrared spectroscopy (FT-RAIRS). We show the complete dissociation of HCl into Cl(-) and H(+) through 3 hydrogen bonds, predominantly by direct reaction with water (80%) and by self-solvation (20%), in full agreement with the prediction of a barrierless process.
authors.affiliation: Laboratoire de Chimie-Physique, Matière et Rayonnement, Université Pierre-et-Marie Curie (UPMC-Univ Paris 06) and CNRS (UMR 7614), 11 rue Pierre-et-Marie-Curie, 75231 Paris Cedex 05, France. philippe.parent@upmc.fr.
authors.forename: Philippe
authors.initials: P
authors.lastname: Parent
authors.forename: Jérôme
authors.initials: J
authors.lastname: Lasne
authors.forename: Guillaume
authors.initials: G
authors.lastname: Marcotte
authors.forename: Carine
authors.initials: C
authors.lastname: Laffon