Multiphonon Resonant Raman Scattering and Photoinduced Charge-Transfer Effects at ZnO鈥揗olecule Interfaces
详细信息 查看全文
- 作者：Zhu Mao ; Wei Song ; Xiangxin Xue ; Wei Ji ; Lei Chen ; John R. Lombardi ; Bing Zhao
- 刊名：The Journal of Physical Chemistry C
- 出版年：2012
- 出版时间：December 27, 2012
- 年：2012
- 卷：116
- 期：51
- 页码：26908-26918
- 全文大小：644K
- 年卷期：v.116,no.51(December 27, 2012)
- ISSN：1932-7455
文摘
Detailed understanding of the underlying mechanisms of surface-enhanced Raman scattering (SERS) remains challenging for different experimental conditions. In this study, a novel laser-driven photoinduced interfacial charge transfer (CT) was observed based on UV鈥搗isible鈥搃nfrared excitation wavelengths (325, 488, 514, 633, and 785 nm) through surface modification of ZnO nanorods by 4-aminothiophenol (PATP). SERS spectra combined with well-characterized surface morphology and optical spectroscopy indicate that the chemical enhancement occurs at visible-infrared excitation but at ultraviolet excitation (325 nm) multiphonon resonant Raman Scattering (MRRS) results in additional strong enhancements of particular Raman transitions through Cu鈥揨nO鈥揚ATP model. The relationships between the excitation photon energies (3.82, 2.54, 2.41, 1.96, and 1.58 eV), and its Raman shift were discussed. We found the strong dependence of the Raman shifts with the exchanges of excitation photon energies. These results highlight the role of excitation energy in determining the interface enhanced Raman scattering for semiconductor-molecule models. This implies that copper sheet under the ZnO improve the interfacial CT in ZnO-molecule and act as an effective donor for inhibiting reversible CT, and there was a strong interaction, which might be regarded as CT resonance process, between PATP molecules and the ZnO surface. This work not only shows a possibility for further understanding the origin of the SERS mechanism from semiconductor substrates but also for exhibits a situ characterization technique for probing the photoinduced interfacial charge-transfer processes.