This article reports on the authors characterization of the surface-enhanced Raman spectroscopy (SERS) spectrum of copper phthalocyanine as a function of excitation wavelength in the 435–635 nm region, using a tunable excitation Raman system.
The authors show that the Raman excitation spectrum within the surface plasmon resonance is dominated by totally symmetric modes in the blue and non-totally symmetric modes in the red. The findings are compared to the authors’ recent theoretical work on the nature of SERS enhancement. The experimental results are interpreted to be a consequence of vibronically coupled intensity borrowing by charge transfer resonances from allowed molecular transitions, enhancing non-totally symmetric modes. (publisher abstract modified)
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Appl. Phys. Lett. 102, 111101 (2013)