title: Femtosecond time-resolved geometry relaxation and ultrafast intramolecular energy redistribution in Ag2Au.
abstract: The ultrafast dynamics of the bimetallic cluster Ag2Au is investigated by pump-probe negative ion-to-neutral-to-positive ion (NeNePo) spectroscopy. Preparation of the neutral cluster in a highly nonequilibrium state by electron detachment from the mass-selected anion, and subsequent probing of the neutral nuclear dynamics through two-photon ionization to the cationic state, leads to strongly probe-energy-dependent transient cation-abundance signals. The origin of this pronounced time and wavelength dependence of the ionization probability on the femtosecond scale is revealed by ab initio theoretical simulations of the transient spectra. Based on the analysis of underlying dynamics, two fundamental processes involving geometry relaxation from linear to triangular structure followed by ultrafast intramolecular vibrational energy redistribution (IVR) have been identified and for the first time experimentally observed in the frame of NeNePo spectroscopy under conditions close to zero electron kinetic energy.
authors.affiliation: Institut für Experimentalphysik, Freie Universität Berlin Arnimallee 14, 14195 Berlin, Germany. tbernhar@physik.fu-berlin.de
authors.forename: Thorsten M
authors.initials: TM
authors.lastname: Bernhardt
authors.forename: Jan
authors.initials: J
authors.lastname: Hagen
authors.forename: Liana D
authors.initials: LD
authors.lastname: Socaciu
authors.forename: Roland
authors.initials: R
authors.lastname: Mitrić
authors.forename: Andreas
authors.initials: A
authors.lastname: Heidenreich
authors.forename: Jérôme
authors.initials: J
authors.lastname: Le Roux
authors.forename: Denisia
authors.initials: D
authors.lastname: Popolan
authors.forename: Mihai
authors.initials: M
authors.lastname: Vaida
authors.forename: Ludger
authors.initials: L
authors.lastname: Wöste
authors.forename: Vlasta
authors.initials: V
authors.lastname: Bonacić-Koutecký
authors.forename: Joshua
authors.initials: J
authors.lastname: Jortner