Probing spin-orbit quenching in Cl (²P) + H₂ via crossed molecular beam scattering

In our previous work we investigated electronically non-adiabatic effects in Cl (²P_3/2,1/2)+D₂ using crossed molecular beam scattering coupled with velocity mapped ion imaging. The prior experiments placed limits on the cross-section for electronically non-adiabatic spin-orbit excitation Cl (²P_3/2)+D₂ →Cl* ( ²P_1/2)+D₂ and electronically non-adiabatic spin-orbit quenching Cl* (²P_1/2)+D₂ → Cl (²P_3/2)+D₂. In the present work, we investigate electronically non-adiabatic spin-orbit quenching for Cl* (²P_1/2)+H₂ which is the required first step for the reaction of Cl* to produce ground state HCl+H products. In these experiments we collide Cl (²P) with H₂ at a series of fixed collision energies using a crossed molecular beam machine with velocity mapped ion imaging detection. Through an analysis of our ion images, we determine the fraction of electronically adiabatic scattering in Cl* +H₂, which allows us to place limits on the cross-section for electronically non-adiabatic scattering or quenching. We determine the following quenching cross-sections σ _quench(2.1 kcal/mol) = 26 ± 21 Ų, σ _quench(4.0 kcal/mol) = 21 ± 49 Ų, and σ _quench(5.6 kcal/mol) = 14 ± 41 Ų.