Exploring the spin-orbit reactivity in the simplest chlorine atom reaction

摘要

The reaction of Cl(~2P) + H_2 -> HCL + H serves as a benchmark for understanding the abstraction mechanism and has been the subject of numerous experimental and theoretical studies. Despite such intensive investigations, the reactivity of the low-lying spin-orbit excited Cl~*(~2P_(1/2))is unknown and has always been assumed to be negligibly small. By exploiting two different sources for generating the Cl(~2P) beam, it is now found that the excited Cl~*(~2P_(1/2)) atom is surprisingly more reactive to H_2 than the ground state Cl(~2P_(3/2)) reagent, overturning conventional wisdom. By using a technique called Doppler-selected time of flight to directly map out the doubly differential cross sections (angle and speed), the detailed dynamical attributes for both spin-orbit states are also elucidated and contrasted for the first time for any bimolecular reaction.