Cd2+-Induced Interfacial Structural Changes of Langmuir-Blodgett Films of Stearic Acid on Solid Substrates: A Sum Frequency Generation Study

Shen Ye, Hiroyuki Noda, Takuma Nishida, Shigeaki Morita, Masatoshi Osawa

研究成果: Article査読

82 被引用数 (Scopus)

抄録

The molecular structures and their stabilities at the outmost-layer of the Langmuir-Blodgett (LB) films of stearic acid on solid substrates have been investigated by a highly surface-sensitive spectroscopic technique, sum frequency generation (SFG), in air and in aqueous solution, using the combination of both normal and deuterated stearic acid. Peaks observed in the SFG spectra are mainly attributed to the terminal methyl group at the outmost layer of the LB films. The SFG spectra in air are virtually identical and are independent of the odd-even property and thickness (1-12) of the LB films, indicating that the even-numbered LB film changes its surface structure after passing through the interface between the water subphase and air, especially when the Cd2+ cation was included in the water subphase. Furthermore, we have demonstrated for the first time using in situ SFG measurement that the interfacial molecular structure at the LB bilayer of stearic acid on the hydrophilic substrates significantly change with immersion in the water subphase containing Cd2+ cation while such a structural change has not been observed in the water subphase without Cd2+. These results clearly indicate that a reorganization process takes place on the surface of the stearic acid bilayer induced by the Cd2+ cation. The electrostatic interaction between the carboxylate headgroup of stearic acid via the Cd2+ cation seems to play an important role in the surface reorganization process both in air and in solution.

本文言語English
ページ(範囲)357-365
ページ数9
ジャーナルLangmuir
20
2
DOI
出版ステータスPublished - 2004 1月 20
外部発表はい

ASJC Scopus subject areas

  • 物理化学および理論化学
  • コロイド化学および表面化学

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