【作者】 张弛；

【导师】 张利剑；

【作者基本信息】 南京大学 ， 材料工程（专业学位）， 2018， 硕士

【摘要】 近年来等离激元光子学成为学术研究的热点。等离激元是光场与自由电子相互作用形成的共振模式,多形成于贵金属与介质之间。在过去二十年间,科学家在理论和实验两方面取得大量进展,通过理论设计与生长/加工技术调控颗粒尺寸、材料、几何形状,从而进一步控制其光学及相关特性。局域表面等离激元会在颗粒附近很小的局域内产生近场增强,从而使得金属纳米颗粒的散射和吸收同时增加,因此很多金属纳米颗粒有很强的吸收效率,在入射光的照射下,光能转变为热能,光热效应在生物医疗、光热成像、金属纳米材料的自组装、光热操控等领域有着广泛的应用,但是微观结构的等离激元光热传输仍有很多规律需要探索,因此,在本论文中我们对不同金属微纳结构的光热传输进行了研究,并讨论其在生化检测与局域温度测量中的应用。本论文具体内容如下:(1)对影响金属纳米颗粒光热效应的因素的研究。通过模拟单个金属纳米颗粒置于衬底不同位置的温度分布,得知改变衬底的结构可以有效的提高金纳米颗粒的温度,为了使温度能迅速上升,形成局域高温,需要使金属纳米颗粒聚集分布,产生聚集效应,同时考虑一些占空比大的纳米结构,所以等离激元光热转换器可以考虑通过设计多孔的微纳结构来实现。(2)研究Au/AAO结构的光热效应及其在表面辅助激光解吸附/离子化质谱(SALDI-MS)中的应用。SALDI效率的提升主要是由孔径尺寸、光吸收、热传导和热容等因素导致的。大孔径的Au/AAO相比小孔径Au/AAO基底显示出较少的分析物碎片。Au/AAO作为SALDI-MS衬底的高效证明了其是优秀的等离激元光热转换器,其中一小部分因素是由于光吸收,而主要原因是其孔径尺寸对热传导的影响。(3)通过研究微纳尺度热传导的规律,校准基于扫描荧光光谱的扫描热显微镜。测量温度与未被扰动样品之间温度差异的影响因素主要是针尖尺寸、针尖与样品的间隙、加热功率和热源尺寸。不同因素对相对温度差异的影响是不同的。改变针尖尖端半径和针尖与热源之间的间隙,相对温度差异波动约10%,而热源功率和热源尺寸对相对温度差异有很大影响。通过仿真结果,我们可以认为样品在温度不太高且选定的荧光纳米颗粒尺寸远小于样品的情况下,这种温度测量方法是行之有效的。另外我们还模拟了探针扫描过程,并用线性显式公式进行了温度预测。定量地测量了温度误差,更好地实现基于扫描荧光光谱的扫描热显微镜的温度测量。更多还原

【Abstract】 Surface plasmon polaritons have attracted a lot of interest recently.Surface plasmons are the hybrid mods between light and free electrons,and normally exist at metal/dielectric interfaces.Over the last two decades,scientists have made significant progresses in both theory and experiment.With theoretical design and advanced nanofabrication techniques,today the material,geometry and consequently the optical properties of plasmonic nanostructure can be control at will,leading to many new exciting applications in various fields.Localized surface plasmons is an important type of resonances,which can generate great enhancement of the scattering and absorption cross-sections,as well as the field strength in the vicinity of plasmonic nanoparticles.Therefore,metal nanoparticles often have a high absorption efficiency,and extraordinarily strong optothermal effects.Today,optothermal effects of plasmonic nanostructures have been widely used in biomedicine,photothermography,self-assembly of metal nanomaterials,and optothermal control,to name a few.In this paper,we have study the heat transfer of different metal micro-nanostructures and discussed its applications in biochemical detection and local temperature measurement:(1)Optothermal effects of metal nanoparticles on substrates.How the light-induced temperature rise of metal nanoparticles is investigated by simulating the temperature distribution of individual metal nanoparticles with different types of thermal contacts with substrates.(2)Optothermal effects of Au/AAO structures and its application in surface-assisted laser desorption/ionization(SALDI)mass spectrometry(MS).How the ionization efficiency is related to the aperture size,light absorption,heat conduction and heat capacity of SALDI substrates is studied.We found that a larger pore size will lead to higher ionization efficiency and less fragmentation.Theoretical analysis shows that this is caused by the pore-size dependent optical and thermal properties of the Au/AAO substrates.(3)Heat transfer at the tip-sample gap in scanning thermal microscopes and the influences on measurement accuracy.We show that the discrepancy between the measured temperature and the temperature of unperturbed sample can be significant,and it is related to many factors,including the tip size,size of tip-sample gap,heating power and heat source size.Simulation results indicate that the temperature measurement method is accurate only when the sample temperature is not too high and the tip size is much smaller than the sample size.更多还原