High-order harmonic generation probing of a ring-opening reaction

TL;DR

This paper investigates how high-harmonic generation (HHG) can be used to probe the ultrafast ring-opening reaction of 1,3-cyclohexadiene, revealing characteristic nonlinear responses for different isomers via TDDFT simulations.

Contribution

It introduces a method to distinguish isomers in real-time using HHG spectra and ellipticities during photoisomerization, based on TDDFT modeling.

Findings

HHG spectra differ significantly between isomers

Electronic excitations influence HHG signals

Potential for ultrafast isomer detection

Abstract

Using Time-Dependent Density Functional Theory (TDDFT) nonlinear nonperturbative response of the molecular system is studied for photoisomerization reaction. The 1,3-cyclohexadiene photoisomerization is probed by the high-harmonic generation (HHG) process induced by the ultrashort few femtosecond intense laser pulse. For each of the long-lived or stable isomers, we present results for HHG spectra and HHG ellipticities, as well as multi-photon ionization. Moreover, the laser-induced electronic excitations are calculated and the effect of excitations on HHG spectra is discussed. We describe the characteristic properties of the nonlinear response for each of the isomers that can be used for ultrafast detection of the isomers by tracking the specific changes in HHG response.