• ab initio calculations;
  • conical intersections;
  • isomerization;
  • molecular dynamics;
  • time- resolved spectroscopy
Thumbnail image of graphical abstract

Coherent photoisomerization is a rare, ultrafast process in which the photon energy activates a selected set of reactive vibrational modes, thus ensuring efficient photomechanical energy conversion. In their Full Paper on page 15296 ff., M. Olivucci, S. Haacke et al. combine experimental and theoretical approaches to investigate this process in a model molecular switch. Transient absorption reveals signatures of a quantum vibrational wave packet that drives the molecular motion from the electronic excited S1 to the ground S0 states, thus mimicking energy conversion in rhodopsin. Pronounced out-of-plane motions are predicted to modulate the π-orbital overlap across the twisted C[DOUBLE BOND]C bond after decay to S0, and are held responsible for the observed oscillations.