Stereodynamical control of resonances in the Cl + H₂ (v = 1, j = 1) → HCl + H reaction

The stereodynamical control of resonance profoundly influences the outcomes of molecular collisions. Here, we perform time-dependent wave packet calculations for the Cl + H₂ (v = 1, j = 1) → HCl + H reaction to investigate how stereodynamical control influences reaction resonances. The results of the dynamical calculations indicate that the backward scattering differential cross section of the HCl (v' = 2) product exhibits two pronounced peaks at collision energies of ∼0.4 eV and ∼0.5 eV. Analysis confirms that these characteristic peaks are attributable to reaction resonances. This work explores the impact of different alignment angles of the H₂ reactant molecule on these two reaction resonances. It is found that the parallel alignment of the H₂ molecule markedly amplifies the intensity of the resonance peaks, while the perpendicular alignment results in a notable suppression of these features. Furthermore, the alignment angle of the reactants significantly influences the scattering direction of the products. Products at the energies of resonances from the head-on collision tend to scatter in the backward direction. In contrast, those from the side-on collision are more likely to scatter forward and sideways.