These are preliminary reports that have not been peer-reviewed. They should not be regarded as conclusive, guide clinical practice/health-related behavior, or be reported in news media as established information. For more information, please see our FAQs.
ODT-SAM-RHEED-Preprint.pdf (1.6 MB)

Structures of Self-Assembled n-Alkanethiols on Gold by Reflection High-Energy Electron Diffraction

submitted on 30.05.2020, 00:11 and posted on 01.06.2020, 12:12 by Mithun Ghosh, Ding-Shyue Yang
TThe structures of long-chain alkanethiols (C18H37SH) chemisorbed on an Au(111) single crystal were investigated using reflection high-energy electron diffraction (RHEED). The primary (√3x√3)R30° structure observed as a major species in the as-deposited films contains gold adatoms below the sulfur headgroups. Between the small ordered domains with the alkyl chains tilting toward six directions are azimuthally disorderly packed regions, with a similar average tilt of 30.2°. In contrast, a significant reduction in the coverage of gold adatoms is found in the thermally-induced (2√3x3)rect phase. This superlattice is shown to contain a mixture of two sulfur arrangements, both of which exhibit a small S‒S distance, and the pairing of the aliphatic chains. A microscopic picture is then given for the structural transition. These findings demonstrate how the RHEED technique may be used to resolve structures of nanometer-thick thin films with multiple orders at the interfaces.


Email Address of Submitting Author


University of Houston


United States

ORCID For Submitting Author


Declaration of Conflict of Interest

The authors declare no competing financial interests.