标题: 雷射聚焦单一金奈米造成温度上升引发二维组装的结构之研究
Two-Dimensional Assembly Formation by Temperature Elevation upon Tightly Focused Laser Irradiation on a Single Gold Nanoparticle
作者: 许孜玮
Hsu, Tzu-Wei
三浦笃志
Miura, Atsushi
应用化学系分子科学硕博士班
关键字: 金奈米;二维组装;雷射;温度上升;溶液;奈米粒子;gold nanoparticle;two-dimensional assembly;laser;temperature elevation;solution;nanoparticle
公开日期: 2011
摘要: 奈米粒子特定的排列结构使其可应用在表面科学、微制造技术、生物技术、实验室晶片以及化学感测原件上。然而奈米粒子的组装在许多不同的奈米尺度下,至今仍受到许多制造上的限制。因此必须建立出一套新的方法可以控制奈米粒子组装在特定的位置上。我们的方法其过程包含了(1)藉由连续波雷射聚焦在选定的金奈米粒子上造成局部的温度上升,(2)热由金奈米粒子传至周围的介质以及悬浮在溶液中的奈米粒子,(3)温度梯度所引起的对流将溶液中的奈米粒子带近至金奈米粒子周围,并形成二维的组装结构。
这篇论文中,我们也探讨了不同的奈米粒子的组装情形。在考虑了上述局部加热及对流所引起的组装过程,我们成功地将此方法分别应用在各种不同的奈米粒子溶液中,并形成其他奈米粒子的二维组装。
我们证明并展示雷射能量、照射时间以及溶液中粒子的浓度如何影响组装的机率和大小。我们的结果明显地显示出组装机率有能量以及粒子浓度的依存性,而组装大小则有能量及照射时间的依存性。较高的能量提供了较广大的加热区并提高对流的效率,而较高的粒子浓度有助于积聚更多的奈米粒子形成组装。实验的结果也支持了我们在局部加热金奈米使温度提高上的理论计算,而这部份是根据雷射参数、热传导系数及吸收截面的计算。由以上实验及计算的结果,我们可以藉由操控不同的雷射能量、照射时间及粒子浓度达到控制组装生成的机制,更可进一步地藉由操控雷射光束在基材上特定的位置产生二维组装的结构。
Specifically ordered architecture composed of nanoparticles provides applications such as surface science, microfabrication, biotechnology, lab-on-chip, and chemical sensors. However, the methods of assembling nanoparticles in fabricating various nanoscale architectures so far are still limited. Therefore, it is necessary to develop a new method to control the positions and integrations of the nanoparticles in a certain architecture. This study covers the processes of (i) local temperature elevation on a target gold nanoparticle by tightly focused continuous-wave laser illumination, (ii) heat transfer from the gold nanoparticle to surrounding medium and then to suspended nanoparticles in the colloidal solution, and (iii) convection flow induced by gradient of temperature in the solution that bring about the nanoparticles into close vicinity area around the target gold nanoparticle, forming two-dimensional assembly formation.
In this study, we observed the assembly of different suspended nanoparticles in aqueous solution. By considering the above mentioned processes of the local temperature elevation and convection flow, we have succeeded in developing a new method which can form a two-dimensional assembly formation of various nanoparticles suspended in aqueous solution.
We have demonstrated that how the parameters of continuous-wave laser beam and colloidal solution such as laser power, irradiation time, and particle density affect on the probability and size of the two-dimensional assembly formation. The present results clearly show that the assembly probability depends on laser power and particle density, and the assembly size depends on laser power and irradiation time. A higher laser power provides a wider heated area and enhances convection flow more efficiently, and a higher particle density contributes to accumulate more nanoparticles to form the assembly. This experimental results are supported by our numerical calculations of local temperature elevation on the target gold nanoparticle based on focused laser beam, thermal conductivity, and absorption cross section. Based on overall experimental and numerical results, by varying laser power, irradiation time, and particle density we can control the assembly formation. Further, with this method we can also control the spatial position of the assembly on the substrate by adjustment of the position of the laser beam.
URI: http://140.113.39.130/cdrfb3/record/nctu/#GT079958516
http://hdl.handle.net/11536/50627
显示于类别:Thesis


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