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Electron induced ortho-meta isomerization of single molecules
V Simic-Milosevic1, M Mehlhorn, K-H Rieder
1Institut für Experimentalphysik, Freie Universität Berlin, Arnimalle 14, 14195 Berlin, Germany. simic@fhi-berlin.mpg.de
Physical Review Letters
|May 16, 2007
Summary
Single chloronitrobenzene molecules isomerize on a copper surface when hit by electrons, a reaction triggered by specific vibrational heating. This electron-induced process facilitates the exchange of chlorine and hydrogen positions within the molecule.
Area of Science:
- Surface science
- Molecular physics
- Scanning probe microscopy
Background:
- Understanding single-molecule reactions is crucial for nanoscale chemistry.
- Electron-induced reactions offer precise control over molecular transformations.
- Chloronitrobenzene isomerization on metal surfaces is a model system for studying chemical dynamics.
Purpose of the Study:
- To investigate the isomerization of single chloronitrobenzene molecules on a Cu(111) surface.
- To determine the mechanism and threshold voltage for electron-induced isomerization.
- To explain the observed reaction based on electron-vibrational coupling.
Main Methods:
- Utilizing a scanning tunneling microscope (STM) at cryogenic temperatures (5 K).
- Inducing molecular isomerization through inelastic electron tunneling.
- Measuring the reaction threshold voltage.
Main Results:
- Successfully induced and verified the isomerization of single chloronitrobenzene molecules.
- Determined a threshold voltage of (227±7) mV for the isomerization reaction.
- Explained the reaction mechanism via electron-induced vibrational heating.
Conclusions:
- The isomerization is initiated by the simultaneous excitation of two molecular vibrational modes.
- Inelastically tunneling electrons transfer energy, leading to vibrational heating.
- This process facilitates the exchange of chlorine and hydrogen positions, driving the isomerization.
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