Structures and growth mechanisms of patterned polycrystals by polarimetric imaging

国家科学基金会化学部的有机和高分子化学项目为纽约大学的Bart Kahr教授提供支持，他将提供对多晶层结构的理解，多晶层具有10微米的特征长度。研究人员阐述了导致这种图案化的机制，介观结构的光学性质，以及在技术和其他科学领域的潜在应用。Kahr教授建议解决一个非常复杂的问题，即利用Mueller矩阵成像偏振(及相关技术)来确定小有机化合物的带状球晶的结构和生长机制。这些多晶系统一直是研究人员早期研究的主题，他们提出了一种简单、单一的生长机制，涉及半径的扭曲。这一提议试图理解这些自组装系统中的生长机制，并在某些情况下揭示新的现象。初步结果表明，扭曲机制实际上并不是光学带状的普遍解释。未来的工作应该会导致对这些系统中非平衡图案形成的起源有更深入的理解。了解和控制手性中尺度结构的自发形成超越了晶体生长的基本问题，并可能导致从反射镜到波导的应用，以及在制备手性薄膜方面的应用。拟议的研究将产生更广泛的影响。这位研究人员致力于从幼儿园开始的化学教育。他发现了耐人寻味的证据，证明结晶学是19世纪德国第一批儿童-S日托机构-课程中涵盖的主题之一。卡尔教授撰写并翻译了有关化学史和结晶学的书籍和文章。他与主要化学书籍的作者保持联系，以确保他的发现及时到达本科生手中。计划为教师开设课程，这些课程是更广泛的外联计划的主要组成部分。这位调查员有过与代表不足的学生群体合作的记录。卡尔教授正计划与当地学校合作，将学生带到他的实验室参与研究项目，希望培养出那些原本永远不会进入研究队伍、准备上大学的科学家。

The Organic and Macromolecular Chemistry Program in the Chemistry Division at the National Science Foundation supports Professor Bart Kahr at New York University, who will provide an understanding of the structures of polycrystalline formations, which have characteristic lenghtscales of 10 micrometers. The investigator addresses the mechanisms leading to such patterning, the optical properties of the meso-structures, and potential applications in technology and in other scientific fields. Professor Kahr proposes to attack a very complex subject, namely, to use to Mueller matrix imaging polarimetry (and related techniques) to determine the structures and growth mechanisms of banded spherulites of small organic compounds. These polycrystalline systems have been the subject of earlier studies by researchers who proposed a simple, single, growth mechanism that involved the twisting of radii. This proposal attempts to understand growth mechanisms in these self-assembling systems and in some cases reveal new phenomena. Preliminary results suggest that the twisting mechanism is not in fact the universal explanation of optical banding. Future work should lead to a much deeper understanding of the origins of the nonequilibrium pattern formation in these systems. Understanding and controlling the spontaneous formation of chiral mesoscale structures transcend fundamental questions of crystal growth, and may lead to applications from mirrors to waveguides, and in producing chiral thin films.The broader impact of the proposed investigations will be significant. The investigator is dedicated to chemical education starting at the kindergarten level. He has found intriguing evidence that crystallography was one of the topics covered in the curriculum of the first children?s day care facilities in Germany in the 19th century. Professor Kahr has written and translated books and articles on the history of chemistry and crystallography. He is in contact with the authors of major chemistry books to insure that his findings reach undergraduate chemistry students in a timely manner. Courses for teachers are planned and these are major components of the broader outreach plan. The investigator has a track record of working with underrepresented groups of students. Professor Kahr is planning on working with local schools to bring students to his lab to participate in research projects with the hope of developing college-bound scientists who would otherwise never enter the pipeline.