The effect of large autoionization decay rates (resonance widths) on cold molecular cross-sections and the reflection phenomenon

Autoionization resonance states are characterized by a complex potential energy surfaces, where the imaginary part is proportional to the decay rate. Sharp changes in the autoionization decay rates, with respect to the reaction coordinates, introduce reflections. That is, when the autoionization decay rate is very small outside the interaction region and large within it, the reactants will be reflected away from the interaction region. Consequently, the reaction is expected to be suppressed. However, no reflections was observed in the collision of $H_2$ with He in the ³P state [Nature Chemistry 7 (11) (2015) 921–926], for which the autoionization decay rate is very large in the interaction region and it is small elsewhere. In this paper, we theoretically investigate the reflection phenomenon within cold-chemistry collisions. Moreover, we present the conditions for which such reactions will not be suppressed due to reflections.