Competing thermodynamic and dynamic factors select molecular assemblies on a gold surface.
Controlling the self-assembly of surface-adsorbed molecules into nanostructures requires understanding physical mechanisms that act across multiple length and time scales. By combining scanning tunneling microscopy with hierarchical ab initio and statistical mechanical modeling of 1,4-substituted benzenediamine (BDA) molecules adsorbed on a gold (111) surface, we demonstrate that apparently simple nanostructures are selected by a subtle competition of thermodynamics and dynamics. Of the collection of possible BDA nanostructures mechanically stabilized by hydrogen bonding, the interplay of intermolecular forces, surface modulation, and assembly dynamics select at low temperature a particular subset: low free energy oriented linear chains of monomers and high free energy branched chains.
Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Thomas K
TK
Haxton
Department of Physics, Columbia University, New York, New York 10027, USA and Brion Technologies, Santa Clara, California 95054, USA.
Hui
H
Zhou
Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA and Department of Physics, University of Ontario Institute of Technology, Oshawa, Ontario L1H 7K4, Canada.
Isaac
I
Tamblyn
Department of Physics, Columbia University, New York, New York 10027, USA and KRISS, Daejeon 305-340, South Korea.
Daejin
D
Eom
Department of Physics, Columbia University, New York, New York 10027, USA and School of Physics, Peking University, Collaborative Innovation Center for Quantum Matter, Beijing 100871, China.
Zonghai
Z
Hu
Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Jeffrey B
JB
Neaton
Department of Physics, Columbia University, New York, New York 10027, USA and Department of Electrical Engineering, Columbia University, New York, New York 10027, USA.
Tony F
TF
Heinz
Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Stephen
S
Whitelam