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等离子体驱动表面催化反应
Plasmon-Driven Surface-Catalyzed Reactions
【作者】 王辉；
【作者基本信息】 重庆大学 ， 凝聚态物理学， 2015， 硕士
【摘要】 金属纳米结构的等离子体光学及其在表面增强拉曼散射效应中的应用为表面催化反应奠定了理论基础,本文主要研究了纳米颗粒-金属膜体系的等离子体驱动表面催化反应,并通过表面增强拉曼散射光谱实验与有限元法理论计算相结合的方法分别讨论表面催化反应的两种效应:电场增强效应与热电子效应。电场增强效应主要根据金属纳米结构中的表面等离子体对局域电磁场的极大增强作用,吸附在金属表面的p-aminothiophenol(PATP)分子在电磁场的作用下耦合生成p,p’-dimercaptoazobenzene(DMAB),其催化反应的结果可以通过表面增强拉曼散射光谱检测出来。不同纳米颗粒-金属膜体系的拉曼光谱不同表明纳米颗粒的数目对催化反应影响很大。由于双颗粒体系可以更有效地将更多的能量局域在纳米间隙中,所以双颗粒体系的电磁场强度和拉曼光谱强度要比单颗粒体系高很多倍,双颗粒体系更容易发生催化反应。热电子效应主要根据表面等离子体在金属表面传播时衰变的一部分光子转换为热电子,这些高能热电子能够将金属表面的4-nitrobenzenethiol(4NBT)分子耦合为p,p’-dimercaptoazobenzene(DMAB),其催化结果同样可以通过表面增强拉曼散射光谱检测出来。在纳米颗粒-金属膜体系中等离子体激发产生的热电子数目与纳米颗粒的数目成正比,由纳米颗粒-金属膜体系的表面电荷分布情况可以知道,在双颗粒体系中激发产生的热电子数目更多,所以双颗粒体系的拉曼光谱强度比单颗粒的拉曼光谱强度高很多倍。另外,我们也讨论了纳米材料、激光波长等因素对表面催化反应的影响。得益于纳米颗粒-金属膜体系结构简单而且容易制备,这种杂化等离子体纳米结构不仅对表面催化反应和热电子效应的研究有很大的帮助,而且在传感器、光子探测、水分解等领域的研究有重大意义。
【Abstract】 Plasmon photonics in metal nano structures and its application in surface enhanced Raman scattering established the theoretical foundation for surface catalysis reaction, this paper, we mainly researched the plasmon driven surface catalysis reaction in metal nanoparticle- film system, and focused both theoretically and experimentally on the two effect of surface catalysis recation: the enhancement of electric field and hot electrons, using surface enhanced Raman scattering and finite element method.The enhancement of electric field is mainly according to the surface plasmons in metal nanostructure can enhance local electromagnetic field, the p-aminothiophenol(PATP) molecule absorbed on metal surface can be coupled and generated the p,p’-dimercaptoazobenzene(DMAB) under the effect of electromagnetic, which can be detected by surface enhanced Raman scattering. The variation of surface Raman scattering spectra in different nanoparticle- film systems indicated the catalysis reaction was large depended on the number of nanoparticles. The higher Raman intensity of DMAB and stronger enhancement of electric field in dimer-film ststem nanogap are caused by effective coupling of light energy on metal film in hybridized plasmonic gap mod and surface catalysis reaction was easily occured in dimer-film system.The hot electrons is mainly based on surface palsmons decay into photons in the propagating process along metal surface while a part of them were converted into hot electrons, these hot electrons with high energy can be catalyzed the 4-nitrobenzenethiol(4NBT) molecule absorbed on metal surface to p,p’-dimercaptoazobenzene(DMAB), which also can be verified by surface enhanced Raman scattering. The number of plasmonic hot electrongeneration in nanoparticle- film system is proportional to the number of nanoparticles.The priority of plasmonic hot electron generation in dimer- film gap is larger than that of monomer- film gap, which analyzed by the surface electric and charge distribution, so the SERS intensity of dimer- film system is stronger than monomer-film system.Additionally, we also study the influence of material and wavelength to surface catalysis reaction. Because of the simple configuration and convenient fabrication of nanoparticle- film system, our work on this hybrid plasmon mode are of great significance not only in the field of surface catalysis and hot electrons, but also in other Plasmon fields such as senor, photon detection, water splitting, ect.