SERS detection of vibrational Stark effect using PCBM-based molecular junctions

ORAL

Abstract

Understanding the interplay of local electric field and vibrational degrees of freedom of molecules are of interest. We fabricate gold bowtie structures with nanometer inter- electrode spacing using controllable electromigration. Those gold nanostructures support highly localized plasmons and have proven to be suitable SERS substrates with single-molecule sensitivity, which enable the study of molecular vibrational and electronic physics. By measuring the Raman emission from the electrically biased PCBM-containing junctions, we observed strong linear shifts on the vibrational energies of PCBM. We will present the experiments as well as preliminary theoretical expectations obtained by DFT calculations. We compare the field driven change of vibrational energies of PCBM with those observed in C60 junctions, which have been reported to exhibit quadratic change of vibrational energies due to bias induced charge variation.

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Authors

  • Yajing Li

    Department of Physics and Astronomy, Rice University

  • Peter Doak

    Department of Chemistry, University of California, Berkeley

  • Pavlo Zolotavin

    Department of Physics and Astronomy, Rice University

  • Jeffrey Neaton

    Univ of California - Berkeley, Molecular Foundry, Lawrence Berkeley National Laboratory, Physics Department, UC Berkeley \& Molecular Foundry, LBNL \& Kavli Energy NanoSciences Institute at Berkeley, Berkeley, University of California at Berkeley, University of California, Berkeley; Lawrence Berkeley National Laboratory, Dept. of Physics, UC Berkeley, Molecular Foundry, Lawrence Berkeley National Laboratory; Department of Physics, University of California-Berkeley, University of California, Berkeley and Lawrence Berkeley National Lab, Molecular Foundry, Lawrence Berkeley National Laboratory, and Department of Physics, UC-Berkeley, Lawrence Berkeley National Laboratory

  • Leeor Kronik

    Weizmann Institute of Science, Department of Materials and Interfaces, Weizmann Institute of Science, Israel, Department of Materials and Interfaces, Weizmann Institute of Science, Weizmann Institute of Science, Rehovoth, IL

  • Douglas Natelson

    Department of Physics and Astronomy, Rice University, Department of Physics \& Astronomy, Rice University