帽状锌纳米结构的制备及其表面等离子体共振特性

Preparation and Surface Plasmon Resonance of Cap-shaped Zinc Nanostructures

利用真空热蒸发法在二氧化硅纳米粒子单层膜上沉积锌薄膜制备了帽状锌纳米结构.采用透射电镜(TEM)、扫描电镜(SEM)、X射线衍射(XRD)和紫外-可见吸收光谱(UV-Vis)对样品的形貌、结构和光学特性进行了表征和研究.SEM照片表明所得到的复合纳米粒子为不完全包裹的帽状结构,且其表面较粗糙.XRD分析结果显示在二氧化硅纳米粒子上沉积的锌膜呈多晶六角密堆结构.吸收光谱研究表明,帽状锌纳米结构在570～760nm范围内具有明显的由纵向双极子表面等离子体共振引起的吸收峰,且随着锌帽层厚度的增加或二氧化硅内核粒径的增大,该吸收峰逐渐红移;当内核粒径增大到500nm时,帽状锌纳米结构在412nm附近还出现了一个四极子共振峰.

Cap-shaped zinc nanostructures were prepared with vacuum thermal evaporation method by de-positing Zn films onto the monolayer arrays of SiO2 nanoparticles.The morphologies,structures,and optical properties of the samples were characterized and investigated by transmission electron microscopy （TEM）,scanning electron microscopy （SEM）,X-ray diffraction （XRD） and UV-Vis absorption spectroscopy.SEM images indicated that the composite nanoparticles were incompletely encapsulated and their surfaces were relatively rough.XRD results showed that the Zn films prepared on the top of SiO2 nanoparticles exhibited a polycrystalline hexagonal structure.Absorption spectra indicated that the cap-shaped zinc nanostructures had obvious absorption bands ranging from 570 to 760 nm,which were attributed to the longitudinal dipole surface plasmon resonance （SPR）.The SPR band was found to red-shift with increasing the thickness of Zn cap or the diameter of SiO2 core.While the core diameter increased to 500 nm,the cap-shaped zinc nanostructures exhibited an additional quadrupole SPR band at around 412 nm.