Ultrafast X-Ray Scattering Measurements of Coherent Structural Dynamics on the Ground-State Potential Energy Surface of a Diplatinum Molecule

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Ultrafast X-Ray Scattering Measurements of Coherent Structural Dynamics on the Ground-State Potential Energy Surface of a Diplatinum Molecule

Kristoffer Haldrup, Gianluca Levi, Elisa Biasin, Peter Vester, Mads Goldschmidt Laursen, Frederik Beyer, Kasper Skov Kjær, Tim Brandt van Driel, Tobias Harlang, Asmus O. Dohn, Robert J. Hartsock, Silke Nelson, James M. Glownia, Henrik T. Lemke, Morten Christensen, Kelly J. Gaffney, Niels E. Henriksen, Klaus B. Møller, and Martin M. Nielsen

Phys. Rev. Lett. 122, 063001 – Published 13 February 2019

Abstract

We report x-ray free electron laser experiments addressing ground-state structural dynamics of the diplatinum anion ${Pt}_{2} {POP}_{4}$ following photoexcitation. The structural dynamics are tracked with $< 100 fs$ time resolution by x-ray scattering, utilizing the anisotropic component to suppress contributions from the bulk solvent. The x-ray data exhibit a strong oscillatory component with period 0.28 ps and decay time 2.2 ps, and structural analysis of the difference signal directly shows this as arising from ground-state dynamics along the PtPt coordinate. These results are compared with multiscale Born-Oppenheimer molecular dynamics simulations and demonstrate how off-resonance excitation can be used to prepare a vibrationally cold excited-state population complemented by a structure-dependent depletion of the ground-state population which subsequently evolves in time, allowing direct tracking of ground-state structural dynamics.

Received 16 July 2018

DOI:https://doi.org/10.1103/PhysRevLett.122.063001

Physics Subject Headings (PhySH)

Atomic & molecular structure Potential energy surfaces

Atomic, Molecular & Optical

Authors & Affiliations

Kristoffer Haldrup¹, Gianluca Levi^2,3, Elisa Biasin^1,4, Peter Vester¹, Mads Goldschmidt Laursen¹, Frederik Beyer¹, Kasper Skov Kjær^1,5,4, Tim Brandt van Driel^1,6, Tobias Harlang^1,5, Asmus O. Dohn^2,7, Robert J. Hartsock⁴, Silke Nelson⁶, James M. Glownia⁶, Henrik T. Lemke^6,8, Morten Christensen¹, Kelly J. Gaffney⁴, Niels E. Henriksen², Klaus B. Møller², and Martin M. Nielsen¹

¹Technical University of Denmark, Department of Physics, Fysikvej 307, DK-2800 Kongens Lyngby, Denmark
²Technical University of Denmark, Department of Chemistry, Kemitorvet 207, DK-2800 Kongens Lyngby, Denmark
³Current address: Science Institute of the University of Iceland, VR-III, 107 Reykjavík, Iceland
⁴PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
⁵Department of Chemical Physics, Lund University, Box 118, S-22100 Lund, Sweden
⁶LCLS, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
⁷Science Institute of the University of Iceland, VR-III, 107 Reykjavík, Iceland
⁸SwissFEL, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland