Coherent structural trapping through wave packet dispersion during photoinduced spin state switching

Research output: Contribution to journalArticle


The description of ultrafast nonadiabatic chemical dynamics during molecular photo-transformations remains challenging because electronic and nuclear configurations impact each other and cannot be treated independently. Here we gain experimental insights, beyond the Born-Oppenheimer approximation, into the light-induced spin-state trapping dynamics of the prototypical [Fe(bpy) 3 ] 2+ compound by time-resolved X-ray absorption spectroscopy at sub-30-femtosecond resolution and high signal-to-noise ratio. The electronic decay from the initial optically excited electronic state towards the high spin state is distinguished from the structural trapping dynamics, which launches a coherent oscillating wave packet (265 fs period), clearly identified as molecular breathing. Throughout the structural trapping, the dispersion of the wave packet along the reaction coordinate reveals details of intramolecular vibronic coupling before a slower vibrational energy dissipation to the solution environment. These findings illustrate how modern time-resolved X-ray absorption spectroscopy can provide key information to unravel dynamic details of photo-functional molecules.


  • Henrik T. Lemke
  • Kasper S. Kjær
  • Robert W. Hartsock
  • Tim B van Driel
  • Matthieu Chollet
  • James M. Glownia
  • Sanghoon Song
  • Diling Zhu
  • Elisabetta Pace
  • Samir F. Matar
  • Martin M. Nielsen
  • Maurizio Benfatto
  • Kelly J. Gaffney
  • Eric Collet
  • Marco Cammarata
External organisations
  • Stanford Linear Accelerator Center (SLAC)
  • Paul Scherrer Institute
  • Technical University of Denmark
  • Stanford University
  • INFN Frascati National Laboratory
  • University of Bordeaux
  • Institut de Physique de Rennes
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Atom and Molecular Physics and Optics
Original languageEnglish
Article number15342
JournalNature Communications
Publication statusPublished - 2017 May 24
Publication categoryResearch