Competitive pathways via nonadiabatic transitions in photodissociation

Photodissociation processes of molecules and radicals involving multiple pa thways and nonadiabatic crossings are studied using the photofragment imagi ng technique and the core-sampling version of time-of-flight spectroscopy. Capabilities and challenges are illustrated by two systems. The isocyanic a cid system demonstrates how interactions among potential energy surfaces ca n change during dissociation. The hydroxymethyl photodecomposition system h ighlights Rydberg-valence interactions common in free radicals. The cross-f ertilization between theory and experiment is emphasized.