Ultrafast Photodynamics of Glucose

Abstract

We have investigated the photodynamics of β-d-glucose employing our field-induced surface-hopping (FISH) method, which allows us to simulate the coupled electron-nuclear dynamics, explicitly including nonadiabatic effects and light-induced excitation. Our results reveal that from the initially populated S and S 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, whereas 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, reveal 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 state through the same types of CIs as observed in the field-free simulations.

Exploring the Excited-State Dynamics of Hydrocarbon Radicals, Biradicals, and Carbenes Using Time-Resolved Photoelectron Spectroscopy and Field-Induced Surface Hopping Simulations

“…For the theoretical simulation of the photodynamics of open-shell species, we have utilized our previously developed field-induced surface-hopping method (FISH) 42 , which has been successfully employed to investigate dynamical processes in a variety of closed-shell molecules [43][44][45][46][47][48][49] .…”

“…For the theoretical simulation of the photodynamics of open-shell species, we have utilized our previously developed field-induced surface-hopping (FISH) method, which has been successfully employed to investigate dynamical processes in a variety of closed-shell molecules. − Briefly, the idea of the FISH method is to propagate the nuclei of the molecular system classically “on the fly” in a specified electronic state and to allow for state switches according to a quantum mechanically calculated hopping probability. The latter is based on solving the time-dependent Schrödinger equation for the electronic degrees of freedom along the classical trajectories, with the energy E i of the i th electronic state, the nonadiabatic coupling d ij and the electronic transition dipole moment μ ij depending on the nuclear trajectory R ( t ).…”