Adsorption of primary substituted hydrocarbons onto solid gallium substrates

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Show simple item record De Silva, Chrishani Maheshwari 2013-04-29T14:43:56Z 2013-04-29T14:43:56Z 2013-04-29
dc.description.abstract Adsorption of a series of primarily substituted hydrocarbons (RX; C[subscript]18H[subscript]37PO(OH)[subscript]2 (ODPA), C[subscript]17H[subscript]35COOH, C[subscript]18H[subscript]37OH, C[subscript]18H[subscript]37NH[subscript]2 and C[subscript]18H[subscript]37SH) onto solid gallium substrates with and without UV/ozone treatment was studied using contact angle goniometry, spectroscopic ellipsometry and cyclic voltammetry (CV). UV/ozone treatment offered a hydrophilic surface (water contact angle ([theta][superscript]water) less than 10°), reflecting the formation of a surface oxide layer with the maximum thickness of ca. 1 nm and possibly the removal of surface contaminants. Upon immersion in a toluene solution of a RX, [theta][superscript]water increased due to adsorption of the RX onto gallium substrates. In particular, UV/ozone-treated gallium substrates (UV-Ga) immersed in an ODPA solution exhibited [theta][superscript]water close to 105°. The ellipsometric thickness of the adsorbed ODPA layer was ca. 2.4 nm and CV data measured in an acetonitrile solution showed significant inhibition of redox reaction on the substrate surface. These results indicate the formation of a densely-packed ODPA monolayer on UV-Ga. The coverage of a C[subscript]17H[subscript]35COOH layer adsorbed onto UV-Ga was lower, as shown by smaller [theta][superscript]water (ca. 99°), smaller ellipsometric thickness (ca. 1.3 nm) and smaller electrode reaction inhibition. Adsorption of the other RX onto UV-Ga was weaker, as indicated by smaller [theta][superscript]water (82-92°). ODPA did not strongly adsorb onto UV-untreated gallium substrates, suggesting that the ODPA adsorption mainly originates from hydrogen bond interaction of a phosphonate group with surface oxide. These results will provide a means for controlling the surface properties of oxide-coated gallium that play an essential role in monolayer conductivity measurements and electroanalytical applications. en_US
dc.description.sponsorship Division of Chemical Sciences, Geosciences and Biosciences, Office of Basic Energy Sciences of the U.S en_US
dc.language.iso en_US en_US
dc.publisher Kansas State University en
dc.subject Adsorption en_US
dc.subject Primary substituted en_US
dc.subject Octadecylphosphonic acid en_US
dc.subject Gallium en_US
dc.title Adsorption of primary substituted hydrocarbons onto solid gallium substrates en_US
dc.type Thesis en_US Master of Science en_US
dc.description.level Masters en_US
dc.description.department Department of Chemistry en_US
dc.description.advisor Takashi Ito en_US
dc.subject.umi Chemistry (0485) en_US 2013 en_US May en_US

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