GOALI: Chiroptical Anisotropy

两个世纪以来，人们一直在努力测量有组织的各向异性介质的手性性质，这在分子和材料手性科学中留下了一个巨大的漏洞。在过去三十年里所学到的一点点东西都是断断续续地来的。为了解开平均，赝标量溶液手旋光效应成数量，可以与电子结构的真实的分子，分子晶体张量的数据库是必需的。它们必须使用一种可靠的、易于采用的方法来衡量，并能产生大量数据，以便进行比较、分析和理解。Mueller矩阵成像偏振法是解决方案，因为它可以同时测定所有线性光学性质，它可以测定不完美样品的去偏振，并且适合于非垂直入射的分析处理。没有移动光学部件的快速装置将需要四个光弹性调制器的同步操作。这一点从未实现过，但将通过俄勒冈州和纽约的博士后研究人员的合作，与俄勒冈州希尔斯伯勒的Hinds仪器公司（光弹性调制器和偏振计的领先开发商）一起进行。需要一个商业化的，交钥匙旋光定向材料是必不可少的，因为手光学各向异性是一个鸿沟太大，一个小组的桥梁。利用这种装置，将测量同晶分子晶体的旋光度，这些晶体有助于解释小的结构扰动。为了避免与激子共振相互作用相关的复杂性，将研究基质晶体中染料的“定向气体”的圆二色性的各向异性。Mueller矩阵显微镜和旋光仪也适用于介观结构材料，例如双折射液晶和手性雕刻超材料。非物质文化遗产整整两百年前（1811年），弗朗索瓦·阿拉戈首次观察到光偏振面沿最高对称性方向沿着穿过石英晶体时发生旋转。有人说，没有一种现象“对化学思想的影响比自然旋光能力更深刻”（Liehr，1954年）。不幸的是，从那时起，几乎不可能测量沿着一般方向的有组织介质（如晶体）中的旋光度，因为光的电磁场在低对称性环境中受到更大的扰动，掩盖了感兴趣的现象。因此，我们仍然对分子中旋光的取向依赖性一无所知，这是一种基本的光-物质相互作用。我们的项目旨在开发一种仪器，用于快速准确地测量任何介质中光的偏振状态，以便我们能够导出基本量。该设备基于光弹性调制器，可以以每秒约50，000次的速率改变光的偏振状态。使用由我们的GOALI合作伙伴Hinds仪器制造的四个这样的调制器，我们可以生成一个复杂的信号，可以通过Arago的同事之一傅立叶的数学技术来处理。我们与布朗克斯科学技术学院建立了关系，这是一所服务不足的公立高中，98%的母语是西班牙语。我们提供，除了在我们的实验室在夏季和学年的研究机会，SAT辅导，在富裕的学区普遍行使的优势。我们相信，创造科学家，特别是那些来自代表性不足的群体，需要首先在学生中发展，一个接一个，科学身份，并确保基本的出席。

TECHNICALThe two-century struggle to measure chiroptical properties of organized, anisotropic media leaves an enormous hole in the science of molecular and materials chirality. What little has been learned during the past three decades has come haltingly. In order to unravel averaged, pseudo-scalar solution chiroptical effects into quantities that can be compared with electronic structures of real molecules, a database of molecular crystal tensors is required. They must be measured using a methodology that is robust, can be easily adopted, and can generate the quantity of data that enables comparison, analysis, and understanding. Mueller matrix imaging polarimetry is the solution because all linear optical properties can be determined simultaneously, it can assay depolarization in imperfect samples, and is suited to the treatment of non-normal incidence analytically. A fast device without moving optical components will require the synchronous operation of four photoelastic modulators. This has never been achieved but will be carried out with Hinds Instruments of Hillsboro, Oregon, a leading developer of photoelastic modulators and polarimeters, through collaboration of postdoctoral researchers in Oregon and New York. The need for a commercial, turnkey polarimeter for oriented materials is essential because chiroptical anisotropy is a chasm too large for one group to bridge. With this device, the optical rotation of isomorphous molecular crystals that lend themselves to the interpretation of small structural perturbations will be measured. To avoid complications associated with excitonic interactions in resonance, the anisotropy of circular dichroism of "oriented gases" of dyes in host crystals will be studied. Mueller matrix microscopes and polarimeters are also applicable to meso-structured materials such as cholesteric liquid crystals and chiral sculpted meta-materials. NON TECHNICALExactly two hundred years ago (1811) François Arago first observed the rotation of the plane of light polarization passing through a crystal of quartz along the direction of highest symmetry. It is been said that no phenomenon "has had so profound an effect on chemical thought as that of natural optical rotatory power" (Liehr, 1954. Unfortunately, since that time it has been almost impossible to measure optical rotation in organized media like crystals along general directions because the electromagnetic field of light suffers greater perturbations in low-symmetry environments that mask the phenomenon of interest. Thus, we remain ignorant about the orientation dependence of optical rotation in molecules, a fundamental light-matter interaction. Our project is aimed at developing an instrument for measuring the polarization state of light in any medium quickly and accurately enough so that we can derive the essential quantities. The device is based on photoelastic modulators that can change the polarization state of light at a rate of ~50,000 times per second. Using four such modulators, built by our GOALI partner, Hinds instruments, we can generate a complex signal that can be treated by the mathematical techniques of one of Arago's colleagues', Fourier. We have established a relationship with the Bronx Academy of Science and Technology, an underserved public high school with 98% native Spanish speakers. We provide, in addition to research opportunities in our lab during the summer and academic year, SAT tutoring, an advantage commonly exercised in wealthy school districts. We are convinced that creating scientists, especially those from underrepresented groups, requires first developing within students, one-by-one, scientific identities, and ensuring that the basics are attended.