Structure and stability of tilted-chain phases of alkanethiols on Au(111)

Journal Article · Fri Sep 01 04:00:00 EDT 2000 · Journal of Chemical Physics

OSTI ID:776629

Barrena, Esther ^[1]; Ocal, Carmen; Salmeron, Miquel

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1. LBNL Library

We present evidence for the existence of ordered tilted-chain phases of self-assembled monolayers of C{sub 18}H{sub 33}SH alkylthiols (C18) on Au(111). Tilted phases have been observed before under compressive stress in thiol and silanes monolayers. In the present experiments with C18, tilted phases have been observed to exist also in the absence of applied pressure. Atomic Force Microscopy (AFM) has been used to determine the thickness and lattice periodicity of the films. Two phases have been found to coexist: an hexagonal one with (*3x*3)R30 degrees periodicity (tilt angle 35 degrees), which is characteristic of complete monolayers, and a less dense one with (2x*3)rect periodicity. This corresponds to a 50 degrees-tilted phase, predicted by a chain-interlocking model. The new phase can be irreversibly transformed into the hexagonal phase by mechanical perturbation with the AFM tip.

• Research Organization: Lawrence Berkeley National Lab., CA (US)
• Sponsoring Organization: USDOE Director, Office of Science. Office of Basic Energy Studies. Division of Materials Sciences (US)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 776629
• Report Number(s): LBNL--46577
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 9 Vol. 114; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ATOMIC FORCE MICROSCOPY
GOLD
PHASE STUDIES
PHASE TRANSFORMATIONS
STABILITY
SURFACE PROPERTIES
THIOLS