Femtosecond dynamics of valence-bond isomers of azines: transition states and conical intersections

In this Letter, we report the ultrafast dynamics of isomerization and ring opening of azines, using femtosecond-resolved mass spectrometry. The experimental results and theoretical DFT/ab initio calculations elucidate the reaction mechanism and indicate the crucial role of conical intersections in driving these forbidden, ground-state processes. The global motion, initiated by fs wavepackets, is an important concept for nonradiative and reactive processes in polyatomics.