Double-well structure and microscopic branching in the O(1D)+HCl reaction

By performing a quasiclassical trajectory study, we have confirmed that the title reaction can take place via different paths even when leading to the same product (microscopic branching). However, contrary to a previous hypothesis, no collinear collisions were found to contribute to the reaction. Therefore, the backward–forward structure of the ClO product angular distribution obtained in the crossed-beam experiment has to be ascribed to the combination of a backward peak associated with insertion-like collisions and a forward peak associated with side attachment of O on Cl. Proper combinations of insertion and attachment contributions also rationalize other properties of the title reaction.