Controlling Nonadiabatic Transitions Through Engineered Ultrafast Laser Fields at Conical Intersections

TL;DR

This study demonstrates how engineered ultrafast laser pulses can precisely control nonadiabatic molecular dynamics at conical intersections, affecting reaction pathways and quantum yields.

Contribution

It introduces a systematic approach to manipulate wave-packet evolution at conical intersections using tailored laser pulse parameters.

Findings

Pulse chirp and duration influence vibrational coherence.

Controlled pulse shaping alters reaction branching ratios.

Wave-packet dynamics can be steered through conical intersections.

Abstract

In this paper, we investigate coherent control of nonadiabatic dynamics at a conical intersection (CI) using engineered ultrafast laser pulses. Within a model vibronic system, we tailor pulse chirp and temporal profile and compute the resulting wave-packet population and coherence dynamics using projections along the reaction coordinate. This approach allows us to resolve the detailed evolution of wave-packets as they traverse the degeneracy region with strong nonadiabatic coupling. By systematically varying pulse parameters, we demonstrate that both chirp and pulse duration modulate vibrational coherence and alter branching between competing pathways, leading to controlled changes in quantum yield. Our results elucidate the dynamical mechanisms underlying pulse-shaped control near conical intersections and establish a general framework for manipulating ultrafast nonadiabatic processes.