title: Deexcitation dynamics of superhydrogenated polycyclic aromatic hydrocarbon cations after soft-x-ray absorption.
abstract: We have investigated the response of superhydrogenated gas-phase coronene cations upon soft x-ray absorption. Carbon (1s)⟶π^{⋆} transitions were resonantly excited at hν=285  eV. The resulting core hole is then filled in an Auger decay process, with the excess energy being released in the form of an Auger electron. Predominantly highly excited dications are thus formed, which cool down by hydrogen emission. In superhydrogenated systems, the additional H atoms act as a buffer, quenching loss of native H atoms and molecular fragmentation. Dissociation and transition state energies for several H loss channels were computed by means of density functional theory. Using these energies as input into an Arrhenius-type cascade model, very good agreement with the experimental data is found. The results have important implications for the survival of polyaromatic hydrocarbons in the interstellar medium and reflect key aspects of graphene hydrogenation.
authors.affiliation: Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands.
authors.forename: G
authors.initials: G
authors.lastname: Reitsma
authors.affiliation: Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands and Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700AV Groningen, The Netherlands.
authors.forename: L
authors.initials: L
authors.lastname: Boschman
authors.affiliation: Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands.
authors.forename: M J
authors.initials: MJ
authors.lastname: Deuzeman
authors.affiliation: Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands.
authors.forename: O
authors.initials: O
authors.lastname: González-Magaña
authors.affiliation: Van Swinderen Institute, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Hoekstra
authors.affiliation: Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700AV Groningen, The Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Cazaux
authors.affiliation: Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands.
authors.forename: R
authors.initials: R
authors.lastname: Hoekstra
authors.affiliation: Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands.
authors.forename: T
authors.initials: T
authors.lastname: Schlathölter