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 experi mental results and theoretical DFT/ab initio calculations elucidate the rea ction mechanism and indicate the crucial role of conical intersections in d riving these forbidden, ground-state processes. The global motion, initiate d by fs wavepackets, is an important concept for nonradiative and reactive processes in polyatomics. (C) 1998 Elsevier Science B.V. All rights reserve d.