Get access

Distinguishing chemical and electromagnetic enhancement in surface-enhanced Raman spectra: The case of para-nitrothiophenol

Authors

  • Martin Thomas,

    1. Institute of Physical Chemistry, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Jena, Germany
    2. Institute of Theoretical Chemistry, University of Vienna, Vienna, Austria
    3. Mulliken Center for Theoretical Chemistry, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
    Search for more papers by this author
  • Stefan Mühlig,

    1. Institute of Condensed Matter Theory and Solid State Optics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Jena, Germany
    Search for more papers by this author
  • Tanja Deckert-Gaudig,

    1. Institute of Photonic Technology e.V., Jena, Germany
    Search for more papers by this author
  • Carsten Rockstuhl,

    1. Institute of Condensed Matter Theory and Solid State Optics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Jena, Germany
    Search for more papers by this author
  • Volker Deckert,

    1. Institute of Physical Chemistry, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Jena, Germany
    2. Institute of Photonic Technology e.V., Jena, Germany
    Search for more papers by this author
  • Philipp Marquetand

    Corresponding author
    1. Institute of Theoretical Chemistry, University of Vienna, Vienna, Austria
    • Correspondence to: Philipp Marquetand, Institute of Theoretical Chemistry, University of Vienna, Währinger Str. 17, 1090 Vienna, Austria.

      E-mail: philipp.marquetand@univie.ac.at

    Search for more papers by this author

Abstract

Surface-enhanced Raman spectra are simulated using a combined classical electrodynamics/real-time time-dependent density functional theory approach and compared to experiments. Emphasis is put on discerning between chemical and electromagnetic enhancement. Therefore, three different calculation scenarios are investigated using para-nitrothiophenol as a test molecule. In the first one, corresponding to electromagnetic enhancement, we simulate the molecule alone with ab initio computations incorporating the electromagnetic field emitted by a nanoparticle. Chemical enhancement is modeled in the second scenario, where we include not only the molecule into the quantum chemistry calculations but also metal atoms of the nanoparticle. Here, any modification of the electromagnetic field due to the nanoparticle is not considered. In the third scenario, the former two setups are combined and demanding simulations of the hybrid system containing the molecule and the metal atoms exposed to a strongly modified electromagnetic field due to the plasmonic properties of the metallic nanoparticles are considered. Results are compared to our experimentally measured spectra. Based on our analysis, we show here on rigorous grounds that the electromagnetic effect leads to increased absolute Raman scattering cross sections but no change of the relative intensities. In contrast, the chemical effect leads to changes in relative peak height and also to newly emerging bands in the spectrum. These findings will have major implications in any study that concerns the interaction of molecules with metallic nanostructures. Copyright © 2013 John Wiley & Sons, Ltd.

Get access to the full text of this article

Ancillary