Ultrafast internal conversion without energy crossing

Abstract

Ultrafast (sub-picosecond) internal conversion can occur between electronic states without energetically accessible conical intersections. For that, the molecule must remain in a region of at least weak nonadiabatic coupling, multiplying the odds of a transition, each with a small probability. This phenomenon is discussed with a simple analytical model correlating the instantaneous probability to the lifetime.

Keywords

• Excited states
• Nonadiabatic dynamics
• Weak coupling
• Gap law
• Computational photochemistry