Direct visual evidence for chemical mechanism of SERRS of pyrazine adsorbed on Ag nanoparticle via charge transfer |
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| Institution: | 1. Dongguan Key Laboratory of Green Energy, City College of Dongguan University of Technology, Dongguan, Guangdong 523419, China;;2. Biosensor Research Centre of Dongguan University of Technology, Dongguan, Guangdong, 523808, China;1. Grupo de Espectroscopia Óptica e Fototérmica, Programa de Pós-Graduação em Recursos Naturais, Universidade Estadual de Mato Grosso do Sul, CP 351, Dourados, MS, Brazil;2. Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil;1. Institute of Laser Engineering, Beijing University of Technology, Beijing 100124, PR China;2. College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, PR China;3. Beijing Engineering Research Center of Laser Technology, Beijing University of Technology, Beijing 100124, PR China;4. Key Laboratory of Trans-scale Laser Manufacturing Technology (Beijing University of Technology), Ministry of Education, Beijing 100124, PR China;5. Beijing Engineering Research Center of 3D Printing for Digital Medical Health, Beijing University of Technology, Beijing 100124, PR China |
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| Abstract: | In this paper, the chemical enhancement of surface-enhanced resonance Raman scattering (SERRS) of pyrazine adsorbed on Ag nanoparticles through charge transfer was experimentally and theoretically investigated. Based on the calculations by density functional theory (DFT) and time-dependent DFT (TD-DFT), we theoretically analyzed the absorption spectra and SERS spectrum of the S-complex of pyrazine–Ag20. The charge transfer in the process of resonant electronic transitions between adsorbed molecule and metal cluster can be visualized by the method of charge difference density. It is a direct evidence for the chemical enhancement mechanism of SERRS of pyrazine molecule adsorbed on Ag nanoparticle via charge transfer between molecule and metal. Additionally, the intracluster charge redistribution was also considered as an evidence for the electromagnetic enhancement. By comparing the experimental and theoretical results, it was demonstrated that the SERRS of the pyrazine molecule absorbed on silver clusters in different incident wavelength regions is dominated by different enhancement mechanisms via the chemical and electromagnetic enhancements. |
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| Keywords: | Surface-enhanced resonance Raman scattering (SERRS) Charge transfer (CT) Charge redistribution (CR) Charge difference densities |
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