Ultrafast inter- and intramolecular vibrational energy transfer between molecules at interfaces studied by time- and polarization-resolved SFG spectroscopy

Susumu Yamamoto, Avishek Ghosh, Han Kwang Nienhuys, Mischa Bonn

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

We present experimental results on femtosecond time-resolved surface vibrational spectroscopy aimed at elucidating the sub-picosecond reorientational dynamics of surface molecules. The approach, which relies on polarization- and time-resolved surface sum frequency generation (SFG), provides a general means to monitor interfacial reorientational dynamics through vibrations inherent in surface molecules in their electronic ground state. The technique requires an anisotropic vibrational excitation of surface molecules using orthogonally polarized infrared excitation light. The decay of the resulting anisotropy is followed in real-time. We employ the technique to reveal the reorientational dynamics of vibrational transition dipoles of long-chain primary alcohols on the water surface, and of water molecules at the water-air interface. The results demonstrate that, in addition to reorientational motion of specific molecules or molecular groups at the interface, inter- and intramolecular energy transfer processes can serve to scramble the initial anisotropy very efficiently. In the two exemplary cases demonstrated here, energy transfer occurs much faster than reorientational motion of interfacial molecules. This has important implications for the interpretation of static SFG spectra. Finally, we suggest experimental schemes and strategies to decouple effects resulting from energy transfer from those associated with surface molecular motion.

Original languageEnglish
Pages (from-to)12909-12918
Number of pages10
JournalPhysical Chemistry Chemical Physics
Volume12
Issue number40
DOIs
Publication statusPublished - 2010 Oct 28
Externally publishedYes

ASJC Scopus subject areas

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

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