title: Ultrafast Charge Transfer of a Valence Double Hole in Glycine Driven Exclusively by Nuclear Motion.
abstract: We explore theoretically the ultrafast transfer of a double electron hole between the functional groups of glycine after K-shell ionization and subsequent Auger decay. Although a large energy gap of about 15 eV initially exists between the two electronic states involved and coherent electronic dynamics play no role in the hole transfer, we find that the double hole is transferred within 3 to 4 fs between both functional ends of the glycine molecule driven solely by specific nuclear displacements and non-Born-Oppenheimer effects. The nuclear displacements along specific vibrational modes are of the order of 15% of a typical chemical bond between carbon, oxygen, and nitrogen atoms and about 30% for bonds involving hydrogen atoms. The time required for the hole transfer corresponds to less than half a vibrational period of the involved nuclear modes. This finding challenges the common wisdom that nuclear dynamics of the molecular skeleton are unimportant for charge transfer processes at the few-femtosecond time scale and shows that they can even play a prominent role. It also indicates that in x-ray imaging experiments, in which ionization is unavoidable, valence electron redistribution caused by nuclear dynamics might be much faster than previously anticipated. Thus, non-Born-Oppenheimer effects may affect the apparent electron densities extracted from such measurements.
authors.affiliation: Center for Free-Electron Laser Science, DESY, Notkestraß e 85, D-22607 Hamburg, Germany.|Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, D-22761 Hamburg, Germany.|SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Li
authors.affiliation: Center for Free-Electron Laser Science, DESY, Notkestraß e 85, D-22607 Hamburg, Germany.|Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, D-22761 Hamburg, Germany.
authors.forename: Oriol
authors.initials: O
authors.lastname: Vendrell
authors.affiliation: Center for Free-Electron Laser Science, DESY, Notkestraß e 85, D-22607 Hamburg, Germany.|Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, D-22761 Hamburg, Germany.|Department of Physics, University of Hamburg, Jungiusstraße 9, D-20355 Hamburg, Germany.
authors.forename: Robin
authors.initials: R
authors.lastname: Santra
mesh_terms: D004583:Electrons; D005998:Glycine / Q000737:chemistry*; D008962:Models, Theoretical; D013816:Thermodynamics
chemical_list: D005998:Glycine