title: Chain-branching control of the atomic structure of alkanethiol-based gold-sulfur interfaces.
abstract: Density functional theory structure calculations at 0 K and simulations at 300 K of observed high-resolution in situ scanning tunneling microscopy (STM) images reveal three different atomic-interface structures for the self-assembled monolayers (SAMs) of three isomeric butanethiols on Au(111): direct binding to the Au(111) surface without pitting, binding to adatoms above a regular surface with extensive pitting, and binding to adatoms with local surface vacancies and some pitting. Thermal motions are shown to produce some observed STM features, with a very tight energy balance controlling the observed structures. Variation of the degree of substitution on the α carbon is found to significantly change the relative energies for interaction of the different types of adatom structures with the surface, while the nature of the surface cell, controlled primarily by inter-adsorbate steric interactions, controls substrate reorganization energies and adsorbate distortion energies. Most significantly, by manipulating these features, chemical control of the adsorbate can produce stable interfaces with surface pitting eliminated, providing new perspectives for technological applications of SAMs.
authors.affiliation: Centre for Clean Environment and Energy, Griffith School of Environment, Griffith University, Gold Coast, QLD 4222, Australia.
authors.forename: Yun
authors.initials: Y
authors.lastname: Wang
authors.forename: Qijin
authors.initials: Q
authors.lastname: Chi
authors.forename: Jingdong
authors.initials: J
authors.lastname: Zhang
authors.forename: Noel S
authors.initials: NS
authors.lastname: Hush
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Reimers
authors.forename: Jens
authors.initials: J
authors.lastname: Ulstrup
mesh_terms: D000327:Adsorption; D000473:Alkanes / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D015394:Molecular Structure; D011789:Quantum Theory; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D000473:Alkanes; D013438:Sulfhydryl Compounds; D006046:Gold