# Ultrafast Photodynamics of Glucose

## TL;DR

This study uses advanced simulations to explore how glucose molecules rapidly return to their ground state after UV excitation, revealing nonradiative decay pathways involving conical intersections within 200 femtoseconds.

## Contribution

It introduces a field-induced surface hopping method (FISH) to simulate coupled electron-nuclear dynamics of glucose, capturing nonadiabatic effects and light-induced excitation explicitly.

## Key findings

- Glucose returns to ground state within 200 fs via conical intersections.
- Excitation populates multiple electronic states nearly equally.
- Decay proceeds predominantly through the S1 state involving specific CIs.

## Abstract

We have investigated the photodynamics of $\beta$-D-glucose employing our field-induced surface hopping method (FISH), which allows us to simulate the coupled electron-nuclear dynamics, including explicitly nonadiabatic effects and light-induced excitation. Our results reveal that from the initially populated S$_{1}$ and S$_{2}$ states, glucose returns nonradiatively to the ground state within about 200 fs. This takes place mainly via conical intersections (CIs) whose geometries in most cases involve the elongation of a single O-H bond, while in some instances ring-opening due to dissociation of a C-O bond is observed. Experimentally, excitation to a distinct excited electronic state is improbable due to the presence of a dense manifold of states bearing similar oscillator strengths. Our FISH simulations explicitly including a UV laser pulse of 6.43 eV photon energy reveals that after initial excitation the population is almost equally spread over several close-lying electronic states. This is followed by a fast nonradiative decay on the time scale of 100-200 fs, with the final return to the ground state proceeding via the S$_{1}$ state through the same types of CIs as observed in the field-free simulations.