Au nanorods were prepared through seed growth method. Their lengths and diameters were controlled by adjusting Ag+ content in the growth solution. Ethyl orthosilicate were hydrolyzed in alkali solutions to obtain SiO2-coated Au nanostructures. Au nanorods with ideal morphologies and sizes could only be obtained under the presence of a certain Ag+ concentration in the growth solution. Without Ag+, only some irregular nanoparticles were generated without nanorods. Longitudinal plasma absorption of Au nanorods shifts first to red shift and then to blue with the increase of Ag+ in the growth solution, while transverse plasma absorption hardly changes. However, longitudinal plasma absorption of silica-coated Au nanorods has a blue shift with the increase of the thickness of silica, while the transverse plasma has a slight red shift. Therefore, by coating Au nanorods with silica and by adjusting their aspect ratio by using different Ag+ concentration in the growth solution, Au nanoparticles can be synthesized for applications requiring absorption in specific UV regions.

中文翻译：

---

Au纳米棒和Aunanorods@SiO2的制备及等离子体共振特性

Au纳米棒是通过种子生长法制备的。它们的长度和直径通过调节生长溶液中的 Ag+ 含量来控制。正硅酸乙酯在碱溶液中水解得到SiO2包覆的Au纳米结构。只有在生长溶液中存在一定浓度的 Ag+ 时才能获得具有理想形态和尺寸的 Au 纳米棒。没有Ag+，只有一些不规则的纳米颗粒产生，没有纳米棒。随着生长溶液中Ag+的增加，Au纳米棒的纵向等离子体吸收先红移，然后蓝移，而横向等离子体吸收几乎没有变化。然而，随着二氧化硅厚度的增加，二氧化硅包覆的Au纳米棒的纵向等离子体吸收有蓝移，而横向等离子体有轻微的红移。所以，