Issue 10, 2020

Intersystem crossing in tunneling regime: T1 → S0 relaxation in thiophosgene

Abstract

The T1 excited state relaxation in thiophosgene has attracted much attention as a relatively simple model for the intersystem crossing (ISC) transitions in polyatomic molecules. The very short (20–40 ps) T1 lifetime predicted in several theoretical studies strongly disagrees with the experimental values (∼20 ns) indicating that the kinetics of T1 → S0 ISC is not well understood. We use the nonadiabatic transition state theory (NA-TST) with the Zhu–Nakamura transition probability and the multireference perturbation theory (CASPT2) to show that the T1 → S0 ISC occurs in the quantum tunneling regime. We also introduce a new zero-point vibrational energy correction scheme that improves the accuracy of the predicted ISC rate constants at low internal energies. The predicted lifetimes of the T1 vibrational states are between one and two orders of magnitude larger than the experimental values. This overestimation is attributed to the multidimensional nature of quantum tunneling that facilitates ISC transitions along the non-minimum energy path and is not accounted for in the one-dimensional NA-TST.

Graphical abstract: Intersystem crossing in tunneling regime: T1 → S0 relaxation in thiophosgene

Supplementary files

Article information

Article type
Paper
Submitted
25 Dec 2019
Accepted
18 Feb 2020
First published
18 Feb 2020

Phys. Chem. Chem. Phys., 2020,22, 5500-5508

Author version available

Intersystem crossing in tunneling regime: T1 → S0 relaxation in thiophosgene

A. O. Lykhin and S. A. Varganov, Phys. Chem. Chem. Phys., 2020, 22, 5500 DOI: 10.1039/C9CP06956A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements