CAREER: Colloidal Sedimentation and Colloidal Clusters: Exploring New Ways for Making Microstructured Materials with Novel Optical Properties

这是一个CAREER实验研究项目，将探索胶体沉积和胶体团簇形成作为产生具有重要光学性质的新材料的基础，如光子带隙。单分散胶体作为未来光子材料的基石显示出巨大的希望，因为它们可以自我组装成晶格重复的晶体，其波长与可见光的波长相同。然而，目前可用的单分散（可结晶）球体的折射率较低，晶体结构仅对光子带隙有利。为了解决第一个问题，本项目将探索胶体材料的流态化作为粒度分离的有效手段。该项目的这一阶段的最终目标是缩小高指数多分散颗粒（如二氧化钛）的尺寸分布，使其能够结晶。该项目的另一个研究阶段将寻求具有较大光子带隙的新型胶体晶体结构。目前的胶体晶体几乎都是由具有球对称相互作用势的粒子生长而成的。小的球形颗粒团簇将具有更复杂的团簇间相互作用势，并有望具有潜在更大带隙的新晶体结构。因此，将探索单分散胶体团簇形成和结晶的技术。该项目的教育部分将涉及公众宣传和与科学博物馆的合作。将开发以巨型肥皂膜为基础的展品，并为高中和大学开发新的肥皂膜物理实验。研究生和本科生将参与拟议研究的所有阶段。一门关于软凝聚态物理的研究生课程也将被开发，以加强俄亥俄州立大学的物理课程。这是一个CAREER项目，研究具有有趣和技术相关光学特性的胶体晶体材料。蛋白石是一种天然的宝石，是一种由相同的微观沙粒组成的胶体晶体。它的虹彩性质显示了胶体晶格对光线的深远影响。计算表明，胶体晶体材料，与蛋白石宝石没有什么不同，被称为光子带隙材料，可以用来弯曲光线绕非常尖锐的曲线，比弯曲玻璃光纤材料要尖锐得多。此外，通过改变沙粒的性质及其结构，可以合成出反射而不透射特定颜色范围的胶体晶体，无论光源的位置如何。当这种材料被用来包裹光纤时，无论转弯有多紧，光都不会泄漏出去。遗憾的是，目前的技术水平，在合成胶体晶体不能产生合适的大小的颗粒，也不能排列胶体颗粒的晶体结构所要求的理论。这个项目解决了这两个问题，因为它提出了分离新胶体并从中构建新胶体晶体的方法。软凝聚态物理的研究可能促进下一代计算和通信技术的发展。该项目的教育部分将涉及公众宣传和与科学博物馆的合作。将开发以巨型肥皂膜为基础的展品，并为高中和大学开发新的肥皂膜物理实验。该项目还通过博物馆展览、高中和大学实验室实验以及高级研究生课程，为教育学生这一相对较新的物理学分支提供了一种极好的手段。

This is a CAREER experimental research project that will explore colloidal sedimentation and colloidal cluster formation as a basis for generating new materials with important optical properties, such as photonic band gaps. Monodisperse colloids show great promise as building blocks for tomorrow's photonic materials since they self assemble into crystals with lattice repeats that are of the order of the wavelength of visible light. Two shortcomings, however, are low index of refraction for currently available monodisperse (crystallizable) spheres and crystal structures only moderately favorable for photonic bandgaps. To address the first issue this project will explore fluidization of colloidal materials as an effective means of particle size segregation. The final goal of this phase of the project is to narrow the size distribution of high index polydisperse particles, such as Titania, so they can be crystallized. The other research phase of the project will seek new colloidal crystal structures which have large predicted photonic bandgaps. Current colloidal crystals are nearly all grown from particles with spherically symmetric interaction potentials. Small clusters of spherical particles will have more complex inter-cluster interaction potentials and promise new crystal structures with potentially larger band gaps. Techniques for monodisperse colloidal cluster formation and crystallization will therefore be explored. The educational portion of the project will involve public outreach and collaboration with science museums. Exhibits based on giant soap films will be developed and new soap film physics experiments will be developed for high schools and colleges. Graduate and undergraduate students will participate in all phases of the proposed research. A graduate course on soft condensed matter physics will also be developed, enhancing the physics curriculum at the Ohio State University.%%%This is a CAREER project that investigates colloidal crystalline materials that have interesting and technologically relevant optical properties. Opal is a naturally occurring gemstone gemstones that is a colloidal crystal built up of identical microscopic sand grains. Its iridescent properties show the profound influence that colloid lattices can have on light rays. Calculations show that colloidal crystalline materials, not unlike opal gems, called photonic bandgap materials, can be used to bend light rays around very sharp curves, much sharper than can be achieved by bending a glass fiber optic material. Further, by altering the properties of the sand grains and their structure, colloidal crystals can be synthesized that will reflect, but not transmit, a particular range of colors, no matter what the position of the light source. When such materials are used to encase optical fibers the light cannot leak out, no matter how tight the turns. . Unfortunately the current state of the art in synthesizing colloidal crystals can not produce the right size particles nor arrange colloid particles in the crystal structures required by theory. This project addresses both these issues as it proposes ways to isolate new colloids and from them build new colloid crystals. This research in soft condensed matter physics may facilitate next generation computing and communications technologies. The educational portion of the project will involve public outreach and collaboration with science museums. Exhibits based on giant soap films will be developed and new soap film physics experiments will be developed for high schools and colleges. The project also provides an excellent means of educating students in this relatively new branch of physics through museum exhibits, high school and college laboratory experiments, and an advanced graduate course.