Semiclassical model of ultrafast photoisomerization reactions

TL;DR

This paper introduces a semiclassical model explaining ultrafast photoisomerization as transitions between quasistationary states in a 1D double well potential, accounting for high transition rates and matching experimental data.

Contribution

It presents a novel semiclassical approach to model ultrafast photoisomerization reactions involving quasistationary states and non-adiabatic transitions, providing insights into reaction dynamics.

Findings

Model explains high transition rates even above the barrier.

Calculations yield realistic reaction quantum yields.

Surprisingly effective for states well above the barrier.

Abstract

In this letter we propose a model which explains ultrafast and efficient photoisomerization reactions as driven by transitions between quasistationary states of one dimensional (1D) double well potential of an excited electronic state. This adiabatic potential is formed as a result of doubly crossing of a decay diabatic potential of the ground electronic state and a bound diabatic potential of the excited state. We calculate the eigenstates and eigenfunctions using the semiclassical connection matrices at the turning and crossing points and the shift matrices between these points. The transitions between the localized in the wells below the adiabatic barrier states are realized by the tunneling and by the double non-adiabatic transitions via the crossing points processes. Surprisingly the behavior with the maximum transition rate keeps going even for the states relatively far above the barrier (2 -4 times the barrier height). Even though a specific toy model is investigated here, when properly interpreted it yields quite reasonable values for a variety of measured quantities, such as a reaction quantum yield, and conversion time.