银团簇纳米颗粒的制备及其光吸收谱性质

 采用自悬浮定向流技术制备银团簇纳米颗粒，理论分析了银团簇的成核机理与影响因素，实验研究了制备条件和工艺。结果表明：惰性气体的冷却效率、气体流速和压强、金属熔球的温度和大小是控制颗粒尺寸大小及分布的关键条件，制备粒径小于10 nm的团簇颗粒须采用氦气为载流气体；团簇颗粒流速越大，颗粒粒径越小，尺寸分布越窄，但颗粒生成数量越少。性能表征说明：制备的颗粒呈较规则的球形，为面心立方结构，分散均匀，表面纯净无氧化，粒径分布窄。理论与实验研究了银团簇纳米颗粒的光学吸收谱性质，证明表面等离子共振吸收峰与颗粒的尺寸有很强的相关性，随着颗粒尺寸的减小，由于量子尺寸效应，吸收峰将发生宽化和蓝移。

Preparation and optical properties of silver nanoclusters

Silver nanoclusters were prepared by flow-levitation technique.The nucleation and growth mechanism of the nanoclusters were studied theoretically,and the experiment conditions and technological parameters were studied experimentally.The morphology,granularity,structure,chemical components and electronic structure properties of the as-grown silver nanoclusters were characterized.The results indicate that the average size and dimension distribution of the nanoparticles mainly depend on the cooling efficiency, flow rate and inert gas pressure of the inert gas,and the temperature and size of the metal drop.Only He was used as the carrying gas for producing particles with an average size less than 10 nm.The optical absorption spectra of Ag nanoclusters show that the value of the surface plasmon absorption peak strongly depends on the size of particles.Because of the quantum size effect,with the decrease of the particle size,the plasmon peak shifts toward the short wavelength while the plasmon band width increases.