Excited-state reactions take place via couplings among near-lying electronic states. These electronic state couplings are mediated by nuclear momenta associated with vibrational motions and become most efficient at conical intersections where two or more electronic states are degenerate at the same nuclear configuration. Thereafter, nonadiabatic reaction pathways are open so that chemical reactions are driven into particular reaction outcomes. Even though conceptual description for nonadiabatic reactions as above is nicely conceived, actual experimental evidences are quite rare. Here, we present experimental cases where conical intersections are spectroscopically characterized and associated nonadiabatic dynamic pathways are identified in energy and time domains. Specifically, predissociation dynamics of thioanisoles in the supersonic jet are thoroughly investigated to unravel detailed mechanism involved in nonadiabatic transitions taking place in the vicinity of the conical intersection encountered along the reaction coordinate.
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