Stuttgart 2012 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 18: Molecular Dynamics
MO 18.3: Vortrag
Donnerstag, 15. März 2012, 14:45–15:00, V38.02
Fragmentation of the protonated water dimer via non-adiabatic pathways after valence photoionization — •Zheng Li1, Oriol Vendrell1, and Robin Santra1, 2 — 1CFEL, DESY, Notkestr. 85, D-22607 Hamburg, Germany — 2Department of Physics, University of Hamburg, D-20355 Hamburg, Germany
The protonated water dimer, (H2O)-H+-(H2O), irradiated with the free-electron laser FLASH at DESY (90 eV), undergoes Coulomb-explosion after losing one of its valence electrons via photoionization[1]. The diversity of valence orbitals available for ionization and the large mobility of the central proton lead to increased complexity of its dynamics. The strong two-body dissociation channel H5O2+→H3O++H2O++e−prevails, yet fragmentation channels involving H+ and neutral fragments need to be experimentally identified. Because of the closely-lying outer valence orbitals and various conical intersections, non-adiabatic effects are presumably important for the overall dynamics. Ab initio potential energy surfaces for the three lowest dicationic states have been computed at the CASSCF(8,11)//Koopmans level. A regularized diabatization scheme has been used to obtain a diabatic representation of the Hamiltonian[2]. The quantum dynamics of the photofragmentation has been investigated using the multi-configuration time-dependent Hartree (MCTDH) method[3], the results unravel the underlying mechanism.
[1] L. Lammich et al., Phys. Rev. Lett. 105, 253003 (2010). [2] H. Koeppel et al., J. Chem. Phys. 115, 2377 (2001). [3] M. H. Beck et al., Physics Reports 324, 1 (2000).