Self-assembled and Langmuir—Blodgett stearic acid monolayers on silver: a comparative reflection—absorption Fourier transform infrared spectroscopic study
1994; Elsevier BV; Volume: 324; Issue: 3 Linguagem: Inglês
10.1016/0022-2860(94)08315-0
ISSN1872-8014
AutoresSang Jung Ahn, Dong Hee Son, Kwan Kim,
Tópico(s)Spectroscopy and Quantum Chemical Studies
ResumoSelf-assembled (SA) and Langmuir—Blodgett (LB) monolayers of stearic acid on the surface of silver have been investigated by reflection—absorption Fourier transform infrared spectroscopy. Stearic acid was adsorbed onto silver as the carboxylate with its two oxygen atoms bound symmetrically to the surface. Although both the SA and the LB monolayers consisted of fully extended trans zigzag carbon chains, a closer examination indicated that the SA monolayers should possess a more ordered crystalline structure than the LB monolayers. The infrared spectral data dictated that the extent of methyl group exposure at the air—film interface was greater in the SA monolayers than in the LB monolayers, in agreement with the contact angle measurement. From a theoretical analysis, the alkyl chains in the two monolayers seemed to be tilted away from the surface by less than 5°, but in opposite directions.
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