The electronic and vibrational properties of meso-tetraphenylporphyrin (mtpp) on silver substrates are investigated using UV-Vis and surface-enhanced resonance Raman scattering (SERRS) spectroscopy. Whereas the vibrational signatures associated with the tetrapyrrole backbone exhibit minor variations throughout sequences of consecutively recorded SERRS spectra, the C=C stretching vibrational modes localized on the meso-phenyl moieties of mtpp exhibit noticeable intensity fluctuations, masked in the average SERRS response. We attribute the observed vibrational state-specific blinking events to conformational changes in mtpp, namely, torsional flexibility which mediates the coupling between the ?-framework of the meso-phenyls and the underlying metal substrate.
Revised: January 21, 2015 |
Published: September 18, 2014
Citation
El-Khoury P.Z., K. Honkala, and W.P. Hess. 2014.Electronic and Vibrational Properties of Meso-Tetraphenylporphyrin on Silver Substrates.Journal of Physical Chemistry A 118, no. 37:8115-8123.PNNL-SA-99895.doi:10.1021/jp412360b