title: Formation and characterisation of the silver hydride nanocluster cation [Ag3H2((Ph2 P)2CH2)](+) and its release of hydrogen.
abstract: Multistage mass spectrometry and density functional theory (DFT) were used to characterise the small silver hydride nanocluster, [Ag3 H2 L](+) (where L=(Ph2 P)2 CH2 ) and its gas-phase unimolecular chemistry. Collision-induced dissociation (CID) yields [Ag2 HL](+) as the major product while laser-induced dissociation (LID) proceeds via H2 formation and subsequent release from [Ag3 H2 L](+) , giving rise to [Ag3 L](+) as the major product. Deuterium labelling studies on [Ag3 D2 L](+) prove that the source of H2 is from the hydrides and not from the ligand. Comparison of TD-DFT absorption patterns obtained for the optimised structures with action spectroscopy results, allows assignment of the measured features to structures of precursors and products. Molecular dynamics "on the fly" reveal that AgH loss is favoured in the ground state, but H2 formation and loss is preferred in the first excited state S1 , in agreement with CID and LID experimental findings. This indicates favourable photo-induced formation of H2 and subsequent release from [Ag3 H2 L](+) , an important finding in context of metal hydrides as a hydrogen storage medium, which can subsequently be released by heating or irradiation with light.
authors.affiliation: Université of Lyon, 69622 (France); Institut des Sciences Analytiques, Université Lyon 1, CNRS UMR 5280 Lyon (France).
authors.forename: Marion
authors.initials: M
authors.lastname: Girod
authors.forename: Marjan
authors.initials: M
authors.lastname: Krstić
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Antoine
authors.forename: Luke
authors.initials: L
authors.lastname: MacAleese
authors.forename: Jérome
authors.initials: J
authors.lastname: Lemoine
authors.forename: Athanasios
authors.initials: A
authors.lastname: Zavras
authors.forename: George N
authors.initials: GN
authors.lastname: Khairallah
authors.forename: Vlasta
authors.initials: V
authors.lastname: Bonačić-Koutecký
authors.forename: Philippe
authors.initials: P
authors.lastname: Dugourd
authors.forename: Richard A J
authors.initials: RA
authors.lastname: O'Hair
keywords: fragmentation channels; hydrogen formation; molecular dynamics; multistage mass spectrometry; photochemistry