Molecular-Resolution Interrogation of a Porphyrin Monolayer by Ultrahigh Vacuum Tip-Enhanced Raman and Fluorescence Spectroscopy

Naihao Chiang, Nan Jiang, Dhabih V. Chulhai, Eric A. Pozzi, Mark C. Hersam, Lasse Jensen, Tamar Seideman, Richard P. Van Duyne

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Abstract

Tip-enhanced Raman scattering (TERS) and optically excited tip-enhanced fluorescence (TEF) of a self-assembled porphyrin monolayer on Ag(111) are studied using an ultrahigh vacuum scanning tunneling microscope (UHV-STM). Through selectively exciting different Q-bands of meso-tetrakis- (3,5-ditertiarybutylphenyl)-porphyrin (H2TBPP), chemical information regarding different vibronic excited states is revealed by a combination of theory and experiment; namely, TERS and time-dependent density functional theory (TDDFT) simulations. The observed TEF spectra suggest a weak coupling of H2TBPP to the substrate due to the bulky t-butyl groups and a possible alternative excited state decay path. This work demonstrates the potential of combining TERS and TEF for studying surface-mounted porphyins on substrates, thus providing insight into porphyrin-sensitized solar cells and catalysis. (Figure Presented).

Original languageEnglish (US)
Pages (from-to)4114-4120
Number of pages7
JournalNano letters
Volume15
Issue number6
DOIs
StatePublished - Jun 10 2015

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All Science Journal Classification (ASJC) codes

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

Cite this

Chiang, N., Jiang, N., Chulhai, D. V., Pozzi, E. A., Hersam, M. C., Jensen, L., Seideman, T., & Van Duyne, R. P. (2015). Molecular-Resolution Interrogation of a Porphyrin Monolayer by Ultrahigh Vacuum Tip-Enhanced Raman and Fluorescence Spectroscopy. Nano letters, 15(6), 4114-4120. https://doi.org/10.1021/acs.nanolett.5b01225