Electronic Control Over Attachment and Self-Assembly of Alkyne Groups on Gold

Transition between the disordered and ordered phase on the Au(111) surface due to reaction induced by the AFM tip. (a) Topographic STM image of the disordered phase with an insert showing the computed flat-lying physisorbed phenylacetylene molecule. (b) image of ordered structure at the same location after the reaction with insert showing the computed up-right geometry. Bottom panel shows the computed energetics for the process.

CNMS Staff Science Highlight

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SignificanceSelf-assembled monolayers are typically produced by a rather inefficient process that involves thermally driven attachment reactions of precursor molecules to a metal surface, followed by a slow and defect-prone molecular reorganization. The electron-induced excitation method demonstrated in this work may therefore enable new and highly controlled approaches to molecular self-assembly on a surface. 

Q. Li, C. Han, M. Fuentes-Cabrera, H. Terrones, B. G. Sumpter, W. Lu, J. Bernholc, J. Yi, Z. Gai, A. P. Baddorf, P. Maksymovych, M. Pan, ACS NANO. DOI: 10.1021/nn303734r

Research Details• CNMS capability: Experiments utilize a home-built scanning

tunneling microscope, with temperature range 25-300 K.• Full-electron computation of molecular orientation and bonding.• Fully reversible all-electron control over alkyne self-assembly.• Alkyne attached to gold without oxidants or thermal excitation.• New method bypasses the thermal bottleneck, creating

opportunities for assembly (new molecules, stimuli, structures and reactions) beyond existing paradigms that require thermal activation.

Scientific AchievementDemonstrated a non-thermal, electron-induced approach to the self-assembly of phenylacetylene molecules on gold that allows for a previously unachievable attachment of the molecules to the surface through the alkyne group.