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Title: Mechanical and charge transport properties of alkanethiol self-assembled monolayers on Au (111) surface: The Role of Molecular Tilt

The relationship between charge transport and mechanical properties of alkanethiol self-assembled monolayers (SAM) on Au(111) films has been investigated using an atomic force microscope with a conductive tip. Molecular tilts induced by the pressure applied by the tip cause stepwise increases in film conductivity. A decay constant {beta} = 0.57 {+-} 0.03 {angstrom}{sup -1} was found for the current passing through the film as a function of tip-substrate separation due to this molecular tilt. This is significantly smaller than the value of {approx} 1 {angstrom}{sup -1} found when the separation is changed by changing the length of the alkanethiol molecules. Calculations indicate that for isolated dithiol molecules S-bonded to hollow sites, the junction conductance does not vary significantly as a function of molecular tilt. The impact of S-Au bonding on SAM conductance is discussed.
Authors:
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Publication Date:
OSTI Identifier:
926165
Report Number(s):
LBNL-69E
Journal ID: ISSN 0743-7463; LANGD5; TRN: US200807%%503
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Langmuir; Journal Volume: 24; Journal Issue: 5; Related Information: Journal Publication Date: 2008
Research Org:
Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
Sponsoring Org:
Materials Sciences Division
Country of Publication:
United States
Language:
English
Subject:
36; BONDING; CHARGE TRANSPORT; DECAY; DITHIOLS; MECHANICAL PROPERTIES; MICROSCOPES