Quantum control of nanochemistry

在化学系大分子、超分子和纳米化学项目的支持下，西北大学的Tamar Seideman教授正在开发用光控制纳米级系统的方法。光可以推动分子中的电子，反过来又对原子核施加力。在金属纳米结构附近，这种效应被夸大了，因为金属纳米结构可以限制光，产生强烈的等离子体场，放大这些力。塞德曼教授和她的团队正在开发理论方法来预测纳米结构附近的等离子体场，这样它们就可以用来控制化学反应，或者通过纳米级电结的电子流动。他们的发现可能会带来理解纳米领域的新方法，并推动光驱动纳米器件的发展。该项目正在开展几项教育和推广活动，包括参与为来自代表性不足群体的本科生和教师提供研究经验的项目，以及建立两个国际学生交流项目。该项目旨在解决三个相互关联的研究挑战。(1)利用时域有限差分方法计算等离子体增强，研究分子开关构象运动的光学控制；密度泛函理论和平板模型确定势能和极化函数；和朗之万方程来研究时间演化。(2)石墨烯纳米结中电子输运的控制将使用非马尔可夫框架进行研究，该框架包括载流子-载流子和载流子-光子耦合的作用。(3)最后，本研究将介绍和探索激光驱动的反应纳米化学，利用相对于分子旋转周期的光场的时不变特性。作为这项工作的一部分，正在开发的数字代码将在科学界广泛传播，使这项工作的影响远远超出塞德曼实验室。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With support from the Macromolecular, Supramolecular, and Nanochemistry Program in the Division of Chemistry, Professor Tamar Seideman at Northwestern University is developing ways to control nanoscale systems with light. Light can push the electrons in a molecule around and in turn, exert forces on the nuclei. The effect is exaggerated near metal nanostructures, which can confine light, creating intense plasmonic fields that amplify these forces. Professor Seideman and her group are developing theoretical methods to predict the plasmonic fields near nanostructures so that they can be used to control chemical reactions, or the flow of electrons through nanoscale electrical junctions. Their discoveries could lead to new ways of understanding the nano-domain and to the advancement of light-driven nanodevices. The project is pursuing several educational and outreach activities, including participation in programs providing research experiences for undergraduate students and teachers from under-represented groups, as well as establishing two international student exchange programs. The project aims to tackle three interrelated research challenges. (1) Optical control of conformational motion in molecular switches will be studied using a finite-difference time-domain approach to compute plasmonic enhancement; density functional theory and a slab model to determine the potential energy and polarizability functions; and the Langevin equation to study time evolution. (2) The control of electron transport in graphene nanojunctions will be investigated using a non-Markovian framework that includes the roles of carrier-carrier and carrier-photon couplings. (3) Finally, this research effort will introduce and explore laser-driven reactive nanochemistry that takes advantage of the time-invariant nature of the optical field relative to the rotational period of the molecules. The numerical code that is being developed as part of the work will be broadly disseminated in the scientific community enhancing the impact of the work well beyond the Seideman laboratory.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.