Self-Assembled Monolayers of Alkylammonium Ions on Mica: Direct Determination of the Orientation of the Alkyl Chains

✍ Scribed by Dorothee Brovelli; Walter R Caseri; Georg Hähner

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 127 KB
• Volume: 216
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1999.6340

✦ Synopsis

Near edge X-ray absorption fine structure spectroscopy was used to study the orientation of the alkyl chains in monolayers of

‫؍‬ methyl and R 2 ‫؍‬ octadecyl), selfassembled on muscovite mica via ion exchange. The alkyl chains adopt a random orientation in the monooctadecylammonium ions. Dimethyldioctadecylammonium ions, however, form a well-ordered self-assembled monolayer. The average tilt angle between the alkyl chains and the surface normal is 38°. The difference between the mono-and the dioctadecylammonium ions reflects at least partially the packing density of the alkyl chains. When adsorbed on muscovite mica, dimethyldioctadecylammonium ions establish monolayers that are similarly well ordered as alkanethiol monolayers on gold.