International Research Fellowship Program: Self-Assembly of Coated Colloidal Particles for Optical Applications

0107357年国际研究员奖励计划使美国科学家和工程师能够在国外进行三到二十四个月的研究。该计划的奖项提供了联合研究的机会，并利用国外独特或互补的设施、专业知识和实验条件。该奖项将支持罗切斯特大学的马修·Z·耶茨博士与德国波茨坦马克斯·普朗克胶体和界面研究所的弗兰克·卡鲁索博士合作，获得为期六个月的博士后研究奖学金。光子晶体是对某些波长的光不透明，但允许传输其他波长的材料。这些材料不透明的波长区域称为光子带隙。光子晶体有望用于下一代通信和计算技术，在这种技术中，信息传输和处理将使用光而不是电子。光子晶体独特的光学性质源于材料折射率在波长附近的长度尺度上的周期性变化。胶体颗粒有序堆积是合成光子晶体的一种很有前途的方法。当单分散大小的胶体颗粒被允许缓慢沉积时，它们将形成一种六角形的堆叠结构，称为“胶体晶体”。本研究项目的目标是将聚合物颗粒包裹一层薄薄的纳米颗粒形成胶体晶体，以改善胶体晶体的光学性质。高折射率纳米粒子，如二氧化钛或硫化铅，以及发光纳米粒子，如硫化镉和镉，都将被用来改变光子晶体的光学性质。Caruso和他的同事最近形成了涂有发光纳米颗粒的聚苯乙烯胶体晶体。UV-Vis光谱表明，发光纳米粒子的存在增加了聚苯乙烯光子晶体的带隙。包覆胶体晶体的光学性质还有待详细研究。要回答的关键问题是光子带隙如何随涂层的厚度、总的颗粒尺寸以及涂层中纳米颗粒的光学性质而变化。

0107357YatesThe International Research Fellow Awards Program enables U.S. scientists and engineers to conduct three to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a six-month postdoctoral research fellowship by Dr. Matthew Z. Yates of the University of Rochester, to work with Dr. Frank Caruso at Max Planck Institute for Colloids and Interfaces in Potsdam, Germany.Photonic crystals are materials that are opaque to certain wavelengths of light while allowing the transmission of other wavelengths. The wavelength region where these materials are opaque is referred to as the photonic band gap. Photonic crystals offer promise for use in the next generation of communications and computing technology in which light is used instead of electrons for information transmission and processing. The unique optical properties of photonic crystals arise from the periodic variation in the refractive index of the material on a length scale near the wavelength of light. One promising route for the synthesis of photonic crystals is the ordered stacking of colloidal particles. When monodisperse sized colloidal particles are allowed to sediment slowly, they will form a hexagonally stacked structure referred to as a "colloidal crystal". It is the goal of this research project to form colloidal crystals from polymer particles coated with a thin layer of nanoparticles to modify optical properties of the colloidal crystal. Both high refractive index nanoparticles such as titanium dioxide or lead sulfide, and luminescent nanoparticles such as CdS and CdTe will be used to modify the optical properties of the photonic crystals. Caruso and coworkers have recently formed colloidal crystals of polystyrene coated with luminescent nanoparticles. The presence of the luminescent nanoparticles enhanced the photonic band gap of the polystyrene photonic crystal, as shown with UV-Vis spectroscopy. The optical properties of coated colloidal crystals remain to be investigated in detail. Key questions to answer are how the photonic band gap varies with the thickness of the coating layer, overall particle size, and optical properties of the nanoparticles in the coating layer.