Rydberg Time-Of-Flight And Imaging Probes Of The Velocity-Dependent Hydrogen Atom Spin Polarization

摘要

Insights into electron spin and nuclei are central to the field of chemical reaction dynamics. Of particular note is the study of spin-polarized hydrogen (SPH) atoms, which result from photodissociation of molecules. Examination of the detailed H-atom spin polarization is achieved by determining the projection of the electron spin onto the probe laser direction. In doing so, its angular distribution, complex dissociation pathways, and coherent excitation mechanisms may be revealed. Approaches to detect SPH atoms are experimentally challenging due to the difficulty associated with probing ground-state H atoms through isolated fine structure levels, which is the only direct way to achieve sensitivity to the ground-state m-distribution. Here, we present a novel methodology for direct detection of spin-polarized hydrogen atoms with high velocity resolution using variations of the Rydberg time-of-flight and ion imaging techniques. The approach described here utilizes three distinct geometries in addition to a unique double-resonance excitation scheme in order to fully characterize the H atom spin-polarization. In doing so, a general probe of multi-surface nonadiabatic dynamics is achieved, sensitive to coherent effects in dissociation along multiple paths, and is applicable to a wide range of critical polyatomic systems.