Observation of multiple vibrational modes in ultrahigh vacuum tip-enhanced Raman spectroscopy combined with molecular-resolution scanning tunneling microscopy

N. Jiang, E. T. Foley, J. M. Klingsporn, M. D. Sonntag, N. A. Valley, J. A. Dieringer, T. Seideman, G. C. Schatz, M. C. Hersam, R. P. Van Duyne

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138 Citations (Scopus)

Abstract

Multiple vibrational modes have been observed for copper phthalocyanine (CuPc) adlayers on Ag(111) using ultrahigh vacuum (UHV) tip-enhanced Raman spectroscopy (TERS). Several important new experimental features are introduced in this work that significantly advance the state-of-the-art in UHV-TERS. These include (1) concurrent sub-nm molecular resolution STM imaging using Ag tips with laser illumination of the tip-sample junction, (2) laser focusing and Raman collection optics that are external to the UHV-STM that has two cryoshrouds for future low temperature experiments, and (3) all sample preparation steps are carried out in UHV to minimize contamination and maximize spatial resolution. Using this apparatus we have been able to demonstrate a TERS enhancement factor of 7.1 × 105. Further, density-functional theory calculations have been carried out that allow quantitative identification of eight different vibrational modes in the TER spectra. The combination of molecular-resolution UHV-STM imaging with the detailed chemical information content of UHV-TERS allows the interactions between large polyatomic molecular adsorbates and specific binding sites on solid surfaces to be probed with unprecedented spatial and spectroscopic resolution.

Original languageEnglish
Pages (from-to)5061-5067
Number of pages7
JournalNano letters
Volume12
Issue number10
DOIs
Publication statusPublished - Oct 10 2012

Keywords

  • density functional theory
  • phthalocyanine
  • scanning tunneling microscopy
  • tip-enhanced Raman spectroscopy
  • ultrahigh vacuum

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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  • Cite this

    Jiang, N., Foley, E. T., Klingsporn, J. M., Sonntag, M. D., Valley, N. A., Dieringer, J. A., Seideman, T., Schatz, G. C., Hersam, M. C., & Van Duyne, R. P. (2012). Observation of multiple vibrational modes in ultrahigh vacuum tip-enhanced Raman spectroscopy combined with molecular-resolution scanning tunneling microscopy. Nano letters, 12(10), 5061-5067. https://doi.org/10.1021/nl2039925