Molecular-Resolution Interrogation of a Porphyrin Monolayer by Ultrahigh Vacuum Tip-Enhanced Raman and Fluorescence Spectroscopy
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- 作者：Naihao Chiang ; Nan Jiang ; Dhabih V. Chulhai ; Eric A. Pozzi ; Mark C. Hersam ; Lasse Jensen ; Tamar Seideman ; Richard P. Van Duyne
- 刊名：Nano Letters
- 出版年：2015
- 出版时间：June 10, 2015
- 年：2015
- 卷：15
- 期：6
- 页码：4114-4120
- 全文大小：465K
- ISSN：1530-6992
文摘
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.