AVS 62nd International Symposium & Exhibition
    Nanometer-scale Science and Technology Monday Sessions
       Session NS+AS+SP-MoA

Paper NS+AS+SP-MoA7
Ultrahigh Vacuum Tip-Enhanced Raman Spectroscopy and Fluorescence of a Self-Assembled Porphyrin Monolayer

Monday, October 19, 2015, 4:20 pm, Room 212B

Session: Optical Spectroscopy at the Nanoscale
Presenter: Naihao Chiang, Northwestern University
Authors: N. Chiang, Northwestern University
N. Jiang, Northwestern University
D. Chulhai, Pennsylvania State University
E. Pozzi, Northwestern University
M.C. Hersam, Northwestern University
L. Jensen, Pennsylvania State University
T. Seideman, Northwestern University
R.P. Van Duyne, Northwestern University
Correspondent: Click to Email
The study of ultrahigh vacuum tip-enhanced Raman and fluorescence spectroscopy (UHV-TERS/TEF) has been raised to an unprecedented level. UHV-TER and TEF spectra for a self-assembled meso-tetrakis-(3,5-di-tertiarybutylphenyl)-porphyrin (H2TBPP) on Ag(111) have been observed with five different laser excitations in the Q-band region. The observed TERS spectra are complemented by the time-dependent density functional theory (TDDFT) simulations. Chemical information of different vibronic excited states is revealed. The observed TEF spectra suggest a weak coupling of H2TBPP to the surface due to the t-butyl groups. Therefore, the strong tip-enhancement is sufficient to overcome the quenching effect of the metal substrate. This study demonstrates the potential of combining TERS and TEF for studying surface-mounted porphyrins, thus setting the stage for future investigation into porphyrin-based photovoltaics and photocatalysis.