Aspects of photoinduced molecular three-body decay

New experimental techniques and novel analysis procedures promote the inves tigation of three-body processes. Photoinduced three-body decay can be stud ied by technologically advanced, challenging coincidence experiments as wel l as by established spectroscopic techniques if physically meaningful decay mechanisms and parameters are introduced. Such kinematic analysis procedur es, based on the revaluation of fragment kinetic energy distributions, are presented, ranging from synchronous concerted via asynchronous concerted to purely sequential decay mechanisms. A Dalitz plot representation of a thre e-body decay is proffered, bridging the gap between established methods and novel coincidence techniques. Results for structurally similar molecules a re presented: phosgene, carbonyl chloride fluoride, and thionyl chloride. C ompeting mechanisms govern the decay of phosgene via the X(1)A(1) ground st ate and the A(1)A(2) excited state potential energy surfaces. Carbonyl chlo ride fluoride behaves similarly, but the larger stability of the COF interm ediate reduces the complexity brought about by decay channel competition an d essentially confirms the phosgene results. Two electronic excited states determine the dynamics of the thionyl chloride decay leading to a competiti on between three- and two-body decay. Fragmentation from the second absorpt ion,band leads to results comparable to the phosgene decay via the A(1)A(2) state.