Abstract
Scanning tunneling microscopy has been used to demonstrate phase segregation in varied composition, two-component self-assembled monolayers on gold. These monolayer films were assembled using CH3(CH2)15SH and CH3O2C(CH2)15SH, two similar alkanethiol molecules which are non-hydrogen-bonding and have identical alkyl chain lengths. X-ray photoelectron spectroscopy, infrared spectroscopy, and ellipsometry have been used to characterize the average chemical compositions and average molecular structures of these films. Scanning tunneling microscopy of single composition, self-assembled monolayers of each of these molecules shows a preponderance of defects which can be attributed to single missing chains. In mixed composition films, we observe nanometer scale molecular domains with time-dependent shapes. These observations have important implications both for the fundamental understanding of solubilities and phase segregation in quasi-two-dimensional mixtures and for applications of self-assembly in which spatial patterns of adsorbate mixtures are important.
Original language | English (US) |
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Pages (from-to) | 7636-7646 |
Number of pages | 11 |
Journal | Journal of Physical Chemistry |
Volume | 98 |
Issue number | 31 |
State | Published - 1994 |
Externally published | Yes |
ASJC Scopus subject areas
- Physical and Theoretical Chemistry