Charge‐transfer contributions in surface‐enhanced Raman scattering from Ag,Ag2S and Ag2Se substrates |
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Authors: | Xiaoqi Fu Tingshun Jiang Qian Zhao Hengbo Yin |
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Abstract: | The degree of charge‐transfer in Ag–4‐mercaptopyridine (Mpy) and Ag2S–4‐Mpy systems is investigated by use of surface‐enhanced Raman spectroscopy (SERS). Ag2S and Ag2Se nanoparticles are prepared on the basis of the former formation of Ag nanoparticles to make the SERS analytical objects comparable. We utilize the intensity of the non‐totally symmetric modes (either b1 or b2) as compared with the totally symmetric a1 modes to measure the degree of charge‐transfer. We find ~25% of charge‐transfer contribution for Ag–4‐Mpy, whereas 81 ~ 93% for Ag2S–4‐Mpy. It means that the charge‐transfer resonance contribution dominates the overall enhancement in SERS of Ag2S–4‐Mpy. Energy level diagram is applied to discuss the likely charge‐transfer transition between Ag, Ag2S, Ag2Se and 4‐Mpy. This article may point out the link among the three main resonance sources and could enable some insights into the electronic pathways available to the metal‐molecule and semiconductor‐molecule systems. Copyright © 2012 John Wiley & Sons, Ltd. |
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Keywords: | degree of charge‐transfer SERS Ag2S energy level diagram symmetry |
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