Exciplex funnel resonances in chemical reaction dynamics: The nonadiabatictunneling case associated with an avoided crossing at a saddle point

We report quantum mechanical calculations on a one-dimensional model of a c hemical reaction with an electronically excited exciplex funnel over the sa ddle point to study the competition between direct reflection from the uppe r diabat and metastable trapping (resonances). Particular emphasis is place d on the effect of the funnel on transition probabilities and delay times a s a function of energy and as a function of the magnitude of the energy gap at the saddle point. Quantum dynamics calculations of energy-dependent tra nsition probabilities for a series of energy gaps reveal a regime where the main effect is diabatic reflectivity in direct, short-lived collisions and another regime where the main effect is a series of collisional resonances .