AVS 57th International Symposium & Exhibition
    Surface Science Tuesday Sessions
       Session SS-TuA

Paper SS-TuA8
A New Mechanism of Atomic Manipulation: Bond-Selective Molecular Dissociation via Thermally Activated Electron Attachment

Tuesday, October 19, 2010, 4:20 pm, Room Picuris

Session: Chemical Dynamics at Surfaces
Presenter: S. Sakulsermsuk, University of Birmingham, UK
Authors: S. Sakulsermsuk, University of Birmingham, UK
P.A. Sloan, University of Birmingham, UK
R.E. Palmer, University of Birmingham, UK
Correspondent: Click to Email
We report a new mechanism of (bond-selective) atomic manipulation in the scanning tunneling microscope (STM). We demonstrate a channel for one-electron induced C-Cl bond dissociation in chlorobenzene molecules chemisorbed on the Si(111)-7x7 surface, at room temperature and above, which is thermally activated. We find an Arrhenius thermal energy barrier to one-electron dissociation of 0.8 ± 0.2 eV, which we correlate explicitly with the barrier between chemisorbed and physisorbed precursor states of the molecule. Thermal excitation promotes the target molecule from a state where one-electron dissociation is suppressed to a transient state where efficient one-electron dissociation, analogous to the gas phase negative ion resonance process, occurs. We expect the mechanism will obtain in many surface systems, and not just in STM manipulation, but in photon and electron beam stimulated (selective) chemistry.