Quantum Control of Atom-Ion Charge Exchange via Light-Induced Conical Intersections

Abstract

Conical intersections are crossing points or lines between two or more adiabatic electronic potential energy surfaces in the multidimensional coordinate space of colliding atoms and molecules. Conical intersections and corresponding nonadiabatic coupling can greatly affect molecular dynamics and chemical properties. In this paper, we predict significant or measurable nonadiabatic effects in an ultracold atom–ion charge-exchange reaction in the presence of laser-induced conical intersections (LICIs). We investigate the fundamental physics of these LICIs on molecular reactivity under unique conditions: those of relatively low laser intensity of 108 W/cm2 and ultracold temperatures below 1 mK. We predict irregular interference effects in the charge-exchange rate coefficients between K and Ca+ as functions of the laser frequency. These irregularities occur in our system due to the presence of two LICIs. To further elucidate the role of the LICIs on the reaction dynamics, we compare these rate coefficients with those computed for a system where the CIs have been “removed”. In the laser frequency window, where conical interactions are present, the difference in rate coefficients can be as large as 1 × 10–9 cm3/s.

Cold Chemistry

“…A key result is that these rates can be small, leading to the possibility of cotrapped samples of both species. The contribution by Li et al makes a bold advance, from merely studying a reaction, to altering the surface on which the reaction occurs . They develop the possibility that a conical intersection can be generated at will by laser fields that couple electronic states of alternative symmetries.…”