Nano-Scale Manipulation of Single-Molecule Conformational Transition Through Vibrational Excitation

TL;DR

This study demonstrates precise control over a single molecule's conformational changes by exciting specific vibrations with tunneling electrons, revealing pathways to engineer molecular functions at the nanoscale.

Contribution

It introduces a method to manipulate molecular conformations via vibrational excitation and external forces, enabling tailored control of single-molecule behavior.

Findings

Multiple transition pathways are driven by distinct vibrational modes.

Vibrational energies and transition probabilities can be tuned by external forces.

External force fields can modulate molecular conformational transitions.

Abstract

On-demand control of molecular actions is essential for realizing single-molecule functional devices. Such a control can be achieved by manipulating interactions between individual molecules and their nanoscale environment. In this study, we manipulate the conformational transition of a single pyrrolidine molecule on a Cu(100) surface by exciting its vibra-tions with tunneling electrons using scanning tunneling microscopy. Multiple transition pathways between two structural states are identified to be driven by distinct vibrational modes, whose corresponding nuclear motions are determined by density functional theory calculations. Tip-induced van der Waals forces and intermolecular interactions enable precise tuning of molecule-environment interactions, allowing modulation of vibrational energies, alteration of transition probabilities, and selection of the lowest energy transition pathway. This work reveals how external force fields in a tunable nanocavity can modulate molecular conformational transitions, offering an approach to deliberately engineer molecule-environment interactions for specific molecular functions.