# Ultrafast Intersystem Crossing in SO$_2$ and Nucleobases

## TL;DR

This paper demonstrates through simulations that intersystem crossing in SO$_2$ and nucleobases occurs on an ultrafast timescale, competing directly with internal conversion processes.

## Contribution

It provides the first detailed simulation-based evidence of ultrafast intersystem crossing in these molecules, highlighting its significance in their photophysics.

## Key findings

- Intersystem crossing occurs within a few hundred femtoseconds.
- It directly competes with internal conversion processes.
- Ultrafast crossing impacts the photostability of nucleobases.

## Abstract

Mixed quantum-classical dynamics simulations show that intersystem crossing between singlet and triplet states in SO$_2$ and in nucleobases takes place on an ultrafast timescale (few 100~fs), directly competing with internal conversion.