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 (P-2(3/2,1/2)) + D-2 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 (P-2(3/2)) + D-2 -> Cl* (P-2(1/2))+ D-2 and electronically non-adiabatic spin-orbit quenching Cl* (P-2(1/2))+ D-2 -> Cl (P-2(3/2))+ D-2. In the present work, we investigate electronically non-adiabatic spin-orbit quenching for Cl* (P-2(1/2))+ H-2 which is the required first step for the reaction of Cl* to produce ground state HCl + H products. In these experiments we collide Cl (P-2) with H-2 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 sigma(quench) (2.1 kcal/mol) = 26 +/- 21 angstrom(2), sigma(quench) (4.0 kcal/mol) = 21 +/- 49 angstrom(2), and squench (5.6 kcal/mol) = 14 +/- 41 angstrom(2).