Ballistic Energy Transport in Molecules

化学系的化学结构、动力学和机理(CSDM-A)项目获得这一奖项，资助杜兰大学的伊戈尔·鲁布佐夫教授和亚历山大·伯林教授研究分子中能量的异常快速运动，即所谓的“弹道能量传输”。最常见的情况是，能量(如热)通过组成材料的电子和原子的随机运动缓慢地在材料中传递(这被称为“热扩散”)。鲁布佐夫教授的研究小组发现，在长分子中储存的能量迅速转移到遥远的地方的系统，就像子弹或弹丸一样。这种异常的能量转移可能会帮助科学家发现具有更好的热传输性能的新材料。参与该项目的研究生和本科生正在接受光学科学、激光光谱学和量子理论方面的培训。PI和共同PI在他们的校园里参加了许多教育活动，包括杜兰·路易斯·斯托克斯路易斯安那州少数民族参与联盟(LS-LAMP)夏季本科生研究培训计划，该计划为在科学方面代表性不足的群体的本科生提供真实的研究经验。伊戈尔·鲁布佐夫教授和亚历山大·伯林教授及其各自的研究小组正在将超快激光光谱(弛豫辅助二维红外光谱(2DIR))与理论建模相结合，以更好地理解分子显著距离上非常快速的能量传输是如何发生的。这些科学家希望回答的一些问题包括：决定弹道运输速度的主要因素是什么，如何提高其效率？传输参数，如效率、速度、波段选择和冷却速度，如何依赖于环境和温度？这些转运参数能被外界刺激控制吗？如何设计分子来进行这种控制？与温度梯度方向相反的弹道传输能有效吗？影响输运的因素包括一级和二级链结构、链结构、源振动模式的性质和能量以及温度。这些研究正在确定最有可能的传输机制，因此可能会提出减少弹道能量传输损失和将能量引导到特定目标的方法。弹道输运机制被认为是分子中能量输运的主要组成部分，特别是具有重复单元的官能团的分子，这是非常常见的。这些研究正在帮助我们理解如何使用弹道运输以及如何操纵其结果。建立使这一过程快速有效或缓慢低效所需的基本原则，可能会影响到在纳米科学和分子电子学中占据中心舞台的一大类问题。除了上述培训和外展活动，该项目还包括设计一门新的本科课程，该课程融合了在该计划中获得的知识，并实施了一项关于2DIR光谱的实验练习。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

With this award, the Chemical Structure, Dynamics and Mechanisms (CSDM-A) Program in the Division of Chemistry is funding Professors Igor Rubtsov and Alexander Burin of Tulane University to investigate unusually rapid movement of energy in molecules, so-called "ballistic energy transport." Most often energy (as heat) is transported slowly through materials through the random motion of electrons and atoms making up the material (this is called "thermal diffusion"). Professor Rubtsov's research group has discovered systems where energy deposited in long molecules is rapidly transferred to distant locations, not unlike a bullet or projectile. This anomalous transfer of energy may help scientists discover new materials with improved thermal transport properties. The graduate and undergraduate students working on this project are receiving training in optical science, laser spectroscopy and quantum theory. The PI and co-PI participate in a number of educational activities on their campus, including the Tulane Louis Stokes Louisiana Alliance for Minority Participation (LS-LAMP) Summer Undergraduate Research Training Program, which provides undergraduate students from groups underrepresented in science with authentic research experiences. Professors Igor Rubtsov and Alexander Burin and their respective research groups are combining ultrafast laser spectroscopy (relaxation-assisted two-dimensional infrared spectroscopy (2DIR)) with theoretical modeling to develop a better understanding of how the very rapid energy transport over molecularly-significant distances occurs. Some of the questions that these scientists hope to answer include: What are the main factors determining the speed of ballistic transport and how to increase its efficiency? How do the transport parameters, such as efficiency, speed, band selection, and cooling rate, depend on the environment and temperature? Can these transport parameters be controlled by external stimuli and how to design molecules for such control? Can the ballistic transport be efficient against the direction of thermal gradient? Among the factors affecting transport to be examined are the primary and secondary chain structure, chain architecture, the nature and energy of the source vibrational mode, and the temperature. These studies are identifying the most likely transport mechanisms and, as such, will likely suggest ways of reducing losses for ballistic energy transport and directing energy to specific targets. The ballistic transport mechanism is considered as a principal component of energy transport in molecules, especially for molecules featuring functional groups with repeating units, which are very common. These studies are helping us understanding how to use the ballistic transport and how to manipulate its outcome. Establishing the fundamental principles needed to make the process either fast and efficient or slow and inefficient could impact a broad class of problems that take center stage in nanoscience and molecular electronics. In addition to the aforementioned training and outreach activities, this project includes the the designing of a novel undergraduate course that incorporates the knowledge obtained in the program and implements an experimental exercise on 2DIR spectroscopy.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.