An accidental resonance mediated predissociation pathway of water molecules excited to the electronic (C)over-tilde state

The predissociation dynamics of water molecules in the electronic (C) over tilde state were studied using the time-resolved photoelectron imaging method. Both vibrationless and vibrationally excited states in the (C) over tilde electronic state were studied, with an emphasis on the vibrational excitation effects on the predissociation dynamics of the (C) over tilde state. Besides the well-known rotationally and non-rotationally mediated predissociation pathways (Proc. Natl. Acad. Sci. U. S. A., 2008, 105, 19148), an accidental resonance mediated predissociation pathway for the first bending mode excited state in the (C) over tilde electronic state of H2O is revealed, providing an excellent example of competition between non-adiabatic decay pathways involving at least five electronic states.