帽状铝纳米粒子的制备及表面等离子共振特性

Synthesis and Surface Plasmonic Resonance of Aluminium Nanocaps

金属纳米材料具有许多独特的物理和化学性质。其中一个重要的光学性质就是表面等离子共振。然而在大多数情况下．金属纳米粒子表面等离子共振所产生的吸收峰被限制在相对狭小的范围内．很难进行调谐。近年来．以电介质为核金属为壳的核壳结构复合纳米材料成功的解决了这一问题．通过设计和剪裁内核的直径与外壳层厚度的比值．可以实现光学性质可调的特性。此类复合材料可被广泛应用于光催化、传感器、光信息存储、生物光子学、生物医学等领域。美国莱斯大学及德州的研究人员利用这类核壳结构纳米材料成功地实现了对体外乳腺肿瘤的杀灭实验。在这种类型的材料中．对称性降低的即不完全包裹的纳米粒子如杯状、帽状、半球壳状、月牙状等核壳结构复合粒子由于其自身特殊的几何结构而对光的响应更为敏感．Halas研究小组采用湿化学还原方法结合纳米尺度的掩膜技术制备出了金壳层的杯状及帽状纳米复合粒子，通过对其光学性能的详细研究发现。在一定偏振条件下，其表面等离子共振所产生的消光系数对光的入射角度有很强的依赖关系。

The aluminium encapsulated silica composite nanoparticles were fabricated by physical metal vacuum evaporation method. The composite particles were characterized and investigated by scanning electron microscopy （SEM） and UV-Visible absorption spectroscopy. SEM showed that the composite particles were incompletely encapsulated and cap-shaped; UV-Visible absorption spectroscopy could be moved in a long wavelength from visible to near-infrared showed that their plasmonic absorption peaks while the diameter of the silica core and the thickness of the cap-shaped shell varied. The tunable resonance of aluminium nanocaps could rival with the counterpart of some noble metals such as gold and silver.