Formation of metal nanoparticles tailored by dynamic oblique deposition for plasmonic applications

利用动态斜角沉积技术，我们证明了在具有强烈各向异性表面形貌的氧化物模板层上直接形成具有准平行主轴的银和金纳米棒。纳米棒的光学性质可以通过改变沉积条件来调节，而不需要任何前后处理，所得到的纳米棒阵列显示出高的表面增强拉曼散射(SERS)活性。除了大面积的高宏观均匀度外，我们的纳米棒阵列还包含高密度的孤立矿物。利用优化的银纳米棒阵列，成功地对罗丹明6G溶液中的微滴进行了表面增强拉曼散射成像，成像的空间分辨率至少达到了几个μm的量级，这些特性适用于生物材料的表面增强拉曼散射成像。此外，我们通过掠角沉积在高温衬底(HT-GREAD)上证明了异常金属晶须的生长，而通常的柱状结构由于加速了表面扩散而完全消失。对于晶须的成核和垂直生长的晶须侧面金属原子的有效供应来说，HT-GRAID是必不可少的。这将首次揭示金属晶须的气相生长机制。

Using a dynamic oblique angle deposition technique, we demonstrate the direct formation of Ag and Au nanorods with quasi-parallel major axes on a template layer of oxide having a strongly anisotropic surface morphology. The optical properties of the nanorods are tuned by varying the deposition conditions without any pre- or posttreatment, and the resulting nanorod arrays exhibit high surface-enhanced Raman scattering (SERS) activity. In addition to high macroscopic uniformity over a large area, our nanorod arrays contain a high density of isolated minerals. Using the optimum Ag nanorod arrays, the SERS imaging of the microdroplets of a rhodamine 6G solution is successfully demonstrated The space resolution of the imaging is of the order of at least a few μm. These features are suitable for the SERS imaging of biomaterials. In addition, we demonstrate the growth of unusual metal whiskers by glancing angle deposition on a high temperature (HT-GLAD) substrate, while the usual columnar structures completely disappear due to accelerated surface diffusion. HT-GLAD is essential fur the nucleation of the whiskers and efficient supply of metal atoms on the side surface of the vertically growing whiskers. HT-GLAD will, for the first time, reveal the mechanisms fm the vapor growth of metal whiskers.