单位点调控作为一种重要的材料修饰手段, 近年来在催化、 能源、 环境等领域中蓬勃发展。 调控单位点, 可以有效地调控表面电荷、 电子结构、 原子空间构型, 从而实现材料整体性能的提升。 在拉曼检测领域, 表面电荷等关键因素被广泛认可并是当下研究热点。 然而, 单位点对表面电荷调控, 乃至对拉曼灵敏度影响尚无系统研究。 该研究全新提出单位点(包括单分子、 单原子、 单原子中心的配体络合物等)的表面电荷调控作用并研究其对拉曼检测灵敏度的影响。 其中, 利用经典的特异性反应: 4-氨基-3-肼基-5-巯基-1,2,4-三唑(AHMT)与甲醛生成6-巯基-5-三唑啉［4,3-b］-s-四嗪(MTT), 使得经单位点AHMT调控的Ag材料具有极低的检测限10-12 mol·L-1, 低于不经单位点AHMT调控表面电荷的10-9 mol·L-1, 实现了对甲醛分子的超低浓度检测。 还研究了单钨原子氧化物调控, 对于非特异性反应中的标准分子、 农药残留分子检测能力的影响。 其中罗丹明6G的检测限可以从10-12 mol·L-1降低到10-14 mol·L-1, 农药福美双的检测限也可以从10-9 mol·L-1降低到10-11 mol·L-1, 据此提出了单位点调控表面电荷方法的普适性。 此外, 经过Zeta电位的测试, 发现经单位点调控的Ag表面电位都有较大变化, 符合库伦正负电荷吸附理论, 这更有利于对待检测分子的捕捉, 也是拉曼检测灵敏度提升的原因, 同时也在机理上解释了单位点调控的普适性。 对深层机理方面也做了许多猜测与研究: 一方面, 由于单位点与基底材料之间存在电荷转移, 因而存在化学增强(CM)过程。 同时, 在Ag表面有显著的电磁场增强(EM), 两种增强机制和单位点体系的协同, 需要进一步通过实验、 理论等, 研究不同单位点的新物理机制； 另一方面, 单位点可能作为一种新的振动模态, 与基底中存在的表面等离子体共振(SPR)、 待测分子的共振协同作用, 使得拉曼散射共振更强, 从而提升拉曼检测灵敏度。 该实验与结论都证实了单位点调控在拉曼检测中的可行性、 必要性, 使单位点在该领域的深入研究成为可能。

As an important means of material modification, single site regulation has developed rapidly in catalysis, energy, environment and other fields. The Surface charge, electronic structure and atomic space configuration can be effectively controlled by adjusting single sites, thus improving the overall properties of materials. In the field of Raman detection, surface charge and other key factors are widely recognized and currently being studied. However, there is no systematic study on the effect of single sites on surface charge regulation or Raman sensitivity. In this paper, the surface charge regulation of single sites (including single molecule, single atom and ligand complex in single atom center) is proposed and its effect on Raman detection sensitivity is studied. Through the classic specific response: the 6-mercapto 5-triazoline ［4,3-B］ -S-tetraazine (MTT) is synthesized with 4-amino-3-hydrazo-5-mercapto-1,2,4-triazole (AHMT) and formaldehyde, resulting in a very low detection limit of 10-12 mol·L-1 for the charge regulated Ag material by single molecule AHMT. It is much lower than the 10-9 mol·L-1 without single AHMT regulation, realizing the detection of formaldehyde molecule ultra-low concentration. We also studied the effects of single tungsten oxide regulation on the detection ability of standard molecules and pesticide residues in nonspecific reactions. Among them, the detection limit of Rhodamine 6G could be decreased from 10-12 to 10-14 mol·L-1, and the detection limit of thiramcould also be decreased from 10-9 to 10-11 mol·L-1. Therefore, the universality of the method of unit point control of surface charge was proposed. In addition, through the test of Zeta potential, it was found that the Ag surface potential regulated by single sites had a great change, which was more conducive to the capture of detection molecules, which was also the reason for the increased sensitivity of Raman detection, and also explained the universality of single sites regulation in the mechanism. Many speculations and research have been made on the deep mechanism: On the one hand, there is a chemical enhancement (CM) process due to the charge transfer between the single sites and the substrate. At the same time, there is a significant Electromagnetic field enhancement (EM) on the surface of Ag. The two enhancement mechanisms and the coordination with single sites system are necessary to further study the new physical mechanism of different single sites through experiments and theories. On the other hand, single sites may act as a new vibration mode, which synergistically interacts with surface plasmon resonance (SPR) and resonance of the molecule to be measured in the substrate to make Raman scattering resonance stronger, thus improving the sensitivity of Raman detection. The experiments and conclusions in this paper confirm the feasibility and necessity of single sites regulation in Raman detection, which makes it possible to further study in this field.