| 1. |
- Shaporenko, A., et al.
(author)
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Odd-even effects in photoemission from terphenyl-substituted alkanethiolate self-assembled monolayers
- 2005
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In: Langmuir 21(10), 4370 (2005).
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Journal article (peer-reviewed)abstract
- Self-assembled monolayers (SAMs) formed from 4,4'-terphenyl-substituted alkanethiols C6H5(C6H4)2(CH2)nSH (TPn, n = 1-6) on polycrystalline (111) gold and silver substrates have been characterized by synchrotron-based high-resolution X-ray photoelectron spectroscopy. The intensities, binding energy positions, and width of most photoemission lines exhibited pronounced odd-even effects, i.e., systematic and periodic variation, depending on either odd or even number of the methylene units in the aliphatic linker of the TPn molecules. The detailed analysis of these effects provides important information on the bonding and arrangement of the chemisorbed sulfur headgroups in the TPn films and balance of the structural forces in alkanethiolate SAMs
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| 2. |
- Shaporenko, A., et al.
(author)
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Spectroscopic characterization of 4´-substituted aromatic self-assembled monolayers on GaAs (100) surface
- 2004
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In: Journal of Physical Chemistry B 108, 17964 (2004).
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Journal article (peer-reviewed)abstract
- High-resolution X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy were applied to characterize GaAs(100) surface engineered by self-assembled monolayers (SAMs) of 4'-substituted aromatic molecules: 4'-methyl-4-mercaptobiphenyl (CH3-BPT) and 4'-hydroxy-4-mercaptobiphenyl (OH-BPT). Both of these molecules formed ordered and densely packed SAMs on GaAs, which were able to protect the substrate from degradation under ambient conditions. The molecular attachment in the SAMs is mediated by As-thiolate bond while the intact aromatic backbones have an upright orientation with average tilt angles of 31.0 and 37.2 for CH3-BPT and OH-BPT films, respectively. The difference in the tilt angle is attributed to a higher (by 7-10%) packing density of the former SAM, suggesting that the character of 4'-substitution affects the quality of the resulting SAM on the GaAs substrate
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| 3. |
- Shaporenko, A, et al.
(author)
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Functionalization of GaAs Surfaces with Aromatic Self-Assembled Monolayers: A Synchrotron-Based Spectroscopic Study
- 2003
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In: Langmuir 19, 4992 (2003).
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Journal article (peer-reviewed)abstract
- Stoichiometric GaAs(100) surfaces were functionalized with monolayers of an aromatic compound, 1,1'-biphenyl-4-thiol (BPT), and the engineered surfaces were studied by synchrotron-based high-resolution X-ray photoelectron spectroscopy and near edge X-ray absorption fine structure spectroscopy. BPT molecules were found to form a well-ordered and densely packed self-assembled monolayer on these substrates. The attachment to the substrate occurs over the thiolate headgroup while the intact biphenyl moieties have an upright orientation with an average tilt angle of 31.5 ± 5. The functionalization of GaAs by BPT was found to prevent an oxidation and contamination of the substrate, keeping the GaAs surface in a pristine state. The surface engineering of GaAs with functionalized aromatic monolayers can provide a crucial link for combining GaAs-based semiconductor nanostructures with bio-organic molecular assemblies
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| 4. |
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