Use of spin-labeling techniques to study the dynamics of Penning-ionization reactions

Spin-labeling techniques, specifically the use of electron-spin-polarized He(2 ${}_{}{}^3{}_{}{}^{}$S) metastable atoms coupled with energy-resolved spin analysis of the product electrons, are used to investigate the dynamics of Penning ionization in collisions involving He(2 ${}_{}{}^3{}_{}{}^{}$S) atoms. Results obtained using ${\mathrm{CO}}_2$, CO, ${\mathrm{Cl}}_2$, and ${\mathrm{O}}_2$ target gases are presented that illustrate the capabilities of this approach. In particular, the data for ${\mathrm{Cl}}_2$ and ${\mathrm{O}}_2$ confirm that ionization via ionic channels is important and show that exchange and spin-orbit effects must be considered.