Ji Wei, Li Linfang, Song Wei, Wang Xinnan, Zhao Bing, Ozaki Yukihiro
School of Chemical Engineering, Dalian University of Technology, Dalian, 116024, China.
State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun, 130012, China.
Angew Chem Int Ed Engl. 2019 Oct 7;58(41):14452-14456. doi: 10.1002/anie.201907283. Epub 2019 Aug 13.
A remarkable enhancement of Raman scattering is achieved by submicrometer-sized spherical ZnO superstructures. The secondary superstructures of ZnO particles with a uniform diameter in the range of 220-490 nm was formed by aggregating ca. 13 nm primary single crystallites. By engineering the superstructure size to induce Mie resonances, leading to an electromagnetic contribution to the SERS enhancement. Meanwhile, a highly efficient charge-transfer (CT) contribution derived from the primary structure of the ZnO nanocrystallites was able to enhance the SERS signals as well. The highest Raman enhancement factor of 10 was achieved for a non-resonant molecule by the synergistic effect of CT and Mie resonances. The Mie resonances scattered near-field effect investigated in the present study provides not only an important guide for designing novel SERS-active semiconductor substrates, but also a coherent framework for modelling the electromagnetic mechanism of SERS on semiconductors.
亚微米级球形ZnO超结构实现了拉曼散射的显著增强。通过聚集约13nm的初级单晶体制备了直径均匀在220 - 490nm范围内的ZnO颗粒的二级超结构。通过设计超结构尺寸以诱导米氏共振，从而对表面增强拉曼散射（SERS）增强产生电磁贡献。同时，源自ZnO纳米微晶初级结构的高效电荷转移（CT）贡献也能够增强SERS信号。通过CT和米氏共振的协同效应，对于非共振分子实现了高达10的最高拉曼增强因子。本研究中所研究的米氏共振散射近场效应不仅为设计新型SERS活性半导体衬底提供了重要指导，也为模拟半导体上SERS的电磁机制提供了一个连贯的框架。
