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簇的形成，作为产生具有重要光学特性的新材料的基础，如光子带隙。单分散胶体显示出作为未来光子材料的构建块的巨大希望，因为它们自组装成具有可见光波长量级的晶格重复的晶体。然而，两个缺点是目前可用的单分散（可结晶）球体的折射率低，并且晶体结构仅适度地有利于光子带隙。为了解决第一个问题，本项目将探索胶体物料流化作为粒度分离的有效手段。该项目这一阶段的最终目标是缩小高折射率多分散颗粒（如二氧化钛）的粒度分布，使其能够结晶。该项目的另一个研究阶段将寻求新的胶体晶体结构，具有大的预测光子带隙。目前的胶体晶体几乎都是从具有球对称相互作用势的粒子中生长出来的。球形颗粒的小团簇将具有更复杂的团簇间相互作用势，并有望产生具有潜在更大带隙的新晶体结构。因此，将探索单分散胶体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。将开发基于巨型肥皂膜的展览，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加拟议研究的所有阶段。还将开发一门关于软凝聚态物理的研究生课程，以加强俄亥俄州州立大学的物理课程。这是一个职业项目，研究胶体晶体材料，具有有趣的和技术相关的光学特性。蛋白石是一种天然存在的宝石，是由相同的微观沙粒组成的胶体晶体。它的彩虹色特性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，不像蛋白石宝石，称为光子带隙材料，可以用来弯曲光线周围非常尖锐的曲线，比弯曲玻璃纤维光学材料可以实现更尖锐。此外，通过改变沙粒的性质及其结构，可以合成胶体晶体，无论光源的位置如何，胶体晶体都将反射但不透射特定范围的颜色。当这种材料被用来包裹光纤时，光就不会泄漏出来，无论匝数有多紧。.目前胶体晶体的合成技术不能制备出合适尺寸的胶体颗粒，也不能将胶体颗粒按理论要求的晶体结构排列。该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。软凝聚态物理学的研究可能会促进下一代计算和通信技术。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。将开发基于巨型肥皂膜的展览，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，为学生提供了一种教育这一相对较新的物理学分支的极好手段。

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.