Abstract
Vibrationally resonant sum-frequency generation (VR-SFG) and spectroscopic ellipsometry (SE) have been used to characterize self-assembled monolayer films of unsubstituted and mononitro-substituted oligo(phenylene-ethynylene) molecules on vapor-deposited Au substrates. When combined with quantum chemical calculations of the relevant transition moment directions, orientation distributions and electronic excitation spectra are obtained. The orientation distribution from VR-SFG is in good agreement with previous IR reflection studies, indicating both molecules are tilted from the surface normal by ∼30°. The calculated resonant hyperpolarizabilities are in good agreement with experimental spectra. The optical polarizability extracted from SE suggests strong intermolecular interactions, consistent with molecular exciton theory.
Original language | English (US) |
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Pages (from-to) | 12547-12559 |
Number of pages | 13 |
Journal | Journal of Physical Chemistry B |
Volume | 108 |
Issue number | 33 |
DOIs | |
State | Published - Aug 19 2004 |
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry