Capture theory models: An overview of their development, experimental verification, and applications to ion-molecule reactions.

Since Arrhenius first proposed an equation to account for the behavior of thermally activated reactions in 1889, significant progress has been made in our understanding of chemical reactivity. A number of capture theory models have been developed over the past several decades to predict the rate coefficients for reactions between ions and molecules-ranging from the Langevin equation (for reactions between ions and non-polar molecules) to more recent fully quantum theories (for reactions at ultracold temperatures). A number of different capture theory methods are discussed, with the key assumptions underpinning each approach clearly set out.

Charge Transfer Reactions between Water Isotopologues and Kr ions.

Astrochemical models often adopt capture theories to predict the behavior of experimentally unmeasured ion-molecule reactions. Here, reaction rate coefficients are reported for the charge transfer reactions of HO and DO molecules with cold, trapped Kr ions. Classical capture theory predictions are found to be in excellent agreement with the experimental findings.

Optimizing the intensity and purity of a Zeeman-decelerated beam.

A pure, state-selected beam of gas-phase radicals is an important tool for the precise study of radical reactions that are astrochemically and atmospherically relevant. Generating such a beam has proven to be an ongoing challenge for the scientific community. Using evolutionary algorithms to optimize the variable experimental parameters, the passage of state- and velocity-selected hydrogen atoms can be optimized as they travel through a 12-stage Zeeman decelerator and a magnetic guide.