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Issue 1, 2012
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A multiscale description of molecular adsorption on gold nanoparticles by nonlinear optical spectroscopy

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Abstract

Nonlinear optical Sum and Difference-Frequency spectroscopies are used to probe and model the surface of thiophenol-functionalised gold nanoparticles grafted on a Si(100) substrate through two different silanization procedures. By scanning the [980–1100 cm−1] infrared spectral range with the CLIO Free Electron Laser, ring deformation vibrations of adsorbed thiophenol are investigated. Quantitative data analysis addresses three levels of organization: microscopic, nanoscopic and molecular. Grafting with p-aminophenyl-trimethoxysilane shows an increase of around 40% in surface density of nanoparticles (Ns) as compared to 3-aminopropyl-triethoxysilane. The relative amplitudes of the resonant and nonresonant contributions to the SFG and DFG spectra are discussed in terms of Ns, Fresnel reflectivity factors and local amplification of the nonlinear signals by coupling to the surface plasmon of the particles. They are shown to quantitatively scale with Ns, as measured by atomic force microscopy. Vibration mode assignment is performed through a critical analysis of literature data on IR and Raman spectroscopies coupled to DFT calculations, for which a methodology specific to molecules adsorbed on gold atoms is discussed.

Graphical abstract: A multiscale description of molecular adsorption on gold nanoparticles by nonlinear optical spectroscopy

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Publication details

The article was received on 07 Apr 2011, accepted on 21 Oct 2011 and first published on 14 Nov 2011


Article type: Paper
DOI: 10.1039/C1CP21091B
Phys. Chem. Chem. Phys., 2012,14, 280-289

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    A multiscale description of molecular adsorption on gold nanoparticles by nonlinear optical spectroscopy

    C. Humbert, O. Pluchery, E. Lacaze, A. Tadjeddine and B. Busson, Phys. Chem. Chem. Phys., 2012, 14, 280
    DOI: 10.1039/C1CP21091B

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