Issue 3, 2022

Role of conical intersection seam topography in the chemiexcitation of 1,2-dioxetanes

Abstract

Chemiexcitation, the generation of electronic excited states by a thermal reaction initiated on the ground state, is an essential step in chemiluminescence, and it is mediated by the presence of a conical intersection that allows a nonadiabatic transition from ground state to excited state. Conical intersections classified as sloped favor chemiexcitation over ground state relaxation. The chemiexcitation yield of 1,2-dioxetanes is known to increase upon methylation. In this work we explore to which extent this trend can be attributed to changes in the conical intersection topography or accessibility. Since conical intersections are not isolated points, but continuous seams, we locate regions of the conical intersection seams that are close to the configuration space traversed by the molecules as they react on the ground state. We find that conical intersections are energetically and geometrically accessible from the reaction trajectory, and that topographies favorable to chemiexcitation are found in all three molecules studied. Nevertheless, the results suggest that dynamic effects are more important for explaining the different yields than the static features of the potential energy surfaces.

Graphical abstract: Role of conical intersection seam topography in the chemiexcitation of 1,2-dioxetanes

Supplementary files

Article information

Article type
Paper
Submitted
03 nov. 2021
Accepted
23 déc. 2021
First published
06 janv. 2022
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2022,24, 1638-1653

Role of conical intersection seam topography in the chemiexcitation of 1,2-dioxetanes

I. Fdez. Galván, A. Brakestad and M. Vacher, Phys. Chem. Chem. Phys., 2022, 24, 1638 DOI: 10.1039/D1CP05028A

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