Department of Microelectronic Science and Engineering, School of Physical Science and Technology, Ningbo University, Ningbo, 315211, China.
Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, 300072, China.
Nat Commun. 2020 Apr 14;11(1):1785. doi: 10.1038/s41467-020-15484-6.
In recent years, surface-enhanced Raman scattering (SERS) of a molecule/metal-semiconductor hybrid system has attracted considerable interest and regarded as the synergetic contribution of the electromagnetic and chemical enhancements from the incorporation of noble metal into semiconductor nanomaterials. However, the underlying mechanism is still to be revealed in detail. Herein, we report an irreversible accumulated SERS behavior induced by near-infrared (NIR) light irradiating on a 4-mercaptobenzoic acid linked with silver and silver-doped titanium dioxide (4MBA/Ag/Ag-doped TiO) hybrid system. With increasing irradiation time, the SERS intensity of 4MBA shows an irreversible exponential increase, and the Raman signal of the Ag/Ag-doped TiO substrate displays an exponential decrease. A microscopic understanding of the time-dependent SERS behavior is derived based on the microanalysis of the Ag/Ag-doped TiO nanostructure and the molecular dynamics, which is attributed to three factors: (1) higher crystallinity of Ag/Ag-doped TiO substrate; (2) photo-induced charge transfer; (3) charge-induced molecular reorientation.
近年来，分子/金属-半导体杂化系统的表面增强拉曼散射（SERS）引起了相当大的兴趣，并被认为是通过将贵金属掺入半导体纳米材料而产生的电磁增强和化学增强的协同贡献。然而，其潜在机制仍有待详细揭示。在此，我们报道了近红外（NIR）光照射到与银和掺银二氧化钛（4MBA/Ag/Ag-doped TiO）杂化系统相连的 4-巯基苯甲酸上所引起的不可逆累积 SERS 行为。随着辐照时间的增加，4MBA 的 SERS 强度呈现出不可逆的指数增长，而 Ag/Ag-doped TiO 衬底的拉曼信号则呈指数下降。基于对 Ag/Ag-doped TiO 纳米结构和分子动力学的微观分析，得出了对时间相关 SERS 行为的微观理解，这归因于三个因素：（1）Ag/Ag-doped TiO 衬底的结晶度更高；（2）光诱导电荷转移；（3）电荷诱导分子重排。
