Elucidating Length and Time Scales of Spatiotemporal Heterogeneity in Supercooled Liquids

在这个由化学系的化学结构，动力学和机制计划支持的项目中，Laura考夫曼教授和她在哥伦比亚大学的博士后同事，研究生和本科生研究人员将研究小分子和模拟模型过冷液体的时空异质性的基本方面。拟议的实验将采用一组精心挑选的探针分子，允许系统的询问的长度和时间尺度的异质性在各种小分子玻璃成型。这些测量将详细说明特别是过冷液体的异质性的空间和时间范围，并可能表明过冷液体的脆弱性和时空异质性的广度之间的潜在联系。除了典型的过冷液体，实验系统显示类似的现象，但被怀疑具有结构异质性的建议。除了这些测量，监测单分子（SM）探针旋转动力学，直接询问平移扩散在SM水平的实验将进行。旋转和平移的同时跟踪将解决关于过冷液体中旋转-平移解耦现象知之甚少的问题，揭示这种行为是否可以存在于单分子水平上。伴随着精心制作的模拟将允许旋转和平移运动被跟踪与拟议的实验类比，并将调查互惠探针主机相互作用的方式，将通知和加强实验结果的解释。实现一个更全面的了解时空异质性的过冷液体是巨大的根本利益，以及在不同领域的应用兴趣，从石油运输细胞的冷冻保存。拟议的工作也将有强烈的教育影响，本科生，研究生和博士后研究人员在考夫曼实验室以及年轻的学生。教授考夫曼已启动了与当地特许学校的关系，目前复杂的流体讲座4 - 6年级的学生，合作开发额外的讲座与他们的科学老师，并翻译实时评估工具在这所学校使用到普通化学课程在哥伦比亚大学。通过在哥伦比亚大学生活质量委员会任职，考夫曼教授将促进向哥伦比亚大学理科学生和教职员工传播关于联邦机构和大学关爱家庭政策的信息，并将协助设计、传播和分析一项关于哥伦比亚大学教职员工使用和理解该大学家事假政策的研究。

In this project supported by the Chemical Structure, Dynamics and Mechanisms Program of the Division of Chemistry, Professor Laura Kaufman, together with her postdoctoral associates, graduate students, and undergraduate researchers at Columbia University will investigate fundamental aspects of spatiotemporal heterogeneity in small molecule and simulated model supercooled liquids. The proposed experiments will employ a set of carefully chosen probe molecules that allow for systematic interrogation of the length and time scales of heterogeneity in a variety of small molecule glass formers. These measurements will detail the spatial and temporal extents of heterogeneity in particular supercooled liquids and may suggest underlying connections between supercooled liquid fragility and breadth of spatiotemporal heterogeneity. Beyond typical supercooled liquids, experiments on systems that display similar phenomenology but are suspected of possessing structural heterogeneity are proposed. In addition to these measurements that monitor single molecule (SM) probe rotational dynamics, experiments that directly interrogate translational diffusion at the SM level will be undertaken. Simultaneous tracking of rotations and translations will resolve questions regarding the poorly understood phenomenon of rotational-translational decoupling in supercooled liquids, revealing whether this behavior can exist on a single molecule level. Accompanying carefully crafted simulations will allow for both rotational and translational motility to be tracked in analogy with the proposed experiments and will investigate reciprocal probe-host interactions in a manner that will inform and strengthen interpretation of experimental results. Achieving a fuller understanding of spatiotemporal heterogeneity in supercooled liquids is of great fundamental interest as well as of applied interest in diverse fields, from petroleum transportation to cryopreservation of cells. The proposed work will also have strong educational impact on undergraduate, graduate, and postdoctoral researchers in the Kaufman laboratory as well as on younger students. Professor Kaufman has initiated a relationship with a local charter school to present lectures on complex fluids to 4th-6th grade students, collaboratively develop additional lectures with their science teacher, and translate real-time assessment tools used in this school into the General Chemistry courses at Columbia University. Through service on Columbia University's Quality of Life Committee, Professor Kaufman will facilitate dissemination of information to Columbia University science students and faculty on federal agency and University-based family friendly policies, and will assist in design, dissemination, and analysis of a study on Columbia University faculty use and perceptions of the University's family leave policies.