Molecular orientation of organic thin films on dielectric solid substrates: A phase-sensitive vibrational SFG study

Aimin Ge, Qiling Peng, Lin Qiao, Nageshwar R. Yepuri, Tamim A. Darwish, Michiya Matsusaki, Mitsuru Akashi, Shen Ye

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)

Abstract

Broadband phase-sensitive vibrational sum frequency generation (SFG) spectroscopy was utilized to study the molecular orientation of molecules adsorbed on dielectric solid substrates. A gold thin film was employed to generate a SFG signal as a local oscillator (LO). To simplify the phase measurement, a self-assembled monolayer (SAM) of octadecyltrichlorosilane (OTS) was used as a standard sample for phase correction of the phase-sensitive SFG measurements on the solid/air interface. It was demonstrated that the absolute orientation of molecules in the LB films on a fused quartz surface can be clearly distinguished by phase-sensitive SFG measurement. In addition, the observation on the SAM of d35-OTS reveals that the two C-H stretching modes for α-CH2 group are in opposite phase. Furthermore, by using the present phase-sensitive SFG setup, the orientation flipping of water molecules on positively and negatively charged solid/liquid interface can be distinguished.

Original languageEnglish
Pages (from-to)18072-18078
Number of pages7
JournalPhysical Chemistry Chemical Physics
Volume17
Issue number27
DOIs
Publication statusPublished - 2015 Jul 21
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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