Some Mechanisms in the Photodissociation of Polyatomic Molecules

The various mechanisms promoting predissociation in polyatomic molecules are reviewed, and illustrated by the spectroscopy of various electronic states of HNO, DNO, NH 3 and ND 3 . The quantum number dependences of the predissociation rates are used to discuss the particular mechanism(s) operating in each case. Recent observations using H‐atom time‐of‐flight spectroscopy of the energy disposal in the photodissociation of NH, through its à state show that a conical intersection in the exit channel has a massive influence on the dissociation dynamics.