# Disentangling electron- and electric field-induced ring-closing reactions in a diarylethene derivative on Ag(111)

## TL;DR

This study investigates how electron and electric field stimuli induce ring-closing reactions in a diarylethene derivative on Ag(111), revealing mechanisms, efficiencies, and the influence of molecular orbitals and electric fields.

## Contribution

It demonstrates the distinct electron- and field-induced reaction mechanisms and provides a detailed analysis of the factors affecting switching efficiency and adsorption configurations.

## Key findings

- Electron-induced reaction mechanism with quantum yield variation from 10^{-14} to 10^{-9}
- Resonant enhancement increases switching efficiency at certain bias voltages
- Electric field alone can induce reactions without current passing through the molecule

## Abstract

Using scanning tunneling microscopy and spectroscopy we investigate the adsorption properties and ring-closing reaction of a diarylethene derivative (C5F-4Py) on a Ag(111) surface. We identify an electron-induced reaction mechanism, with a quantum yield varying from $10^{-14}-10^{-9}$ per electron upon variation of the bias voltage from $1-2$ V. We ascribe the drastic increase in switching efficiency to a resonant enhancement upon tunneling through molecular orbitals. Additionally, we resolve the ring-closing reaction even in the absence of a current passing through the molecule. In this case the electric-field can modify the reaction barrier, leading to a finite switching probability at 4.8 K. A detailed analysis of the switching events shows that a simple plate-capacitor model for the tip-surface junction is insufficient to explain the distance dependence of the switching voltage. Instead, describing the tip as a sphere is in agreement with the findings. We resolve small differences in the adsorption configuration of the closed isomer, when comparing the electron- and field-induced switching product.