Ye S.,State Key Laboratory Coordination Chemistry |
Fang L.,State Key Laboratory Coordination Chemistry |
Qing X.,State Key Laboratory Coordination Chemistry |
Lu Y.,State Key Laboratory Coordination Chemistry
Journal of Raman Spectroscopy | Year: 2010
Surface-enhanced Raman scattering (SERS) spectra of Ag@polypyrrole (PPy) nanoparticles with both 488 and 1064 nm excitation were investigated. Experimental results as well as theoretical analysis demonstrated that electromagnetic (EM) enhancement and charge transfer (CT) both rebounded to the SERS effect of Ag@PPy nanoparticles. When near-IR excitation (1064 nm) was used for the SERS measurements, the contribution from CT was amplified relative to that from EM because the energy of the near-IR excitation is far from the surface plasmon resonance of the nanosized Ag particles. The increased doping level of PPy, leading to optimal energy matching between the Fermi levels of the Ag nanoparticles and the energy levels in PPy molecules, could obviouslyenhance the SERS signal. These results suggested that the SERStechnique wasan effective tool for investigating the doping effect and interface interaction in metal-conductingpolymer composite nanoparticles. In particular, the SERS technique with near-IR excitation could give more information regarding the contribution of the charge-transfer mechanism to the spectral enhancement of this kind of system. Copyright © 2010 John Wiley & Sons, Ltd.