Ultrafast Dynamics of Electronic Excited States: Photocatalysis and Photomagnetism

在这个由化学结构、动力学和机制项目- a （CSDM-A）和化学系化学仪器项目资助的项目中，密歇根大学的Kevin J. Kubarych教授和他的研究生和本科生正在研究分子结构、动力学和功能之间的基本关系，这些分子由光驱动，有望极大地重塑二氧化碳转化和信息存储的方法。在这两类系统中，用于还原二氧化碳的光催化剂和光磁体，关键的化学起点涉及吸收光的分子，在激发态中执行其初始功能步骤。Kubarych教授和他的团队将利用基于超快二维红外（2D-IR）光谱和相关方法的新型实验技术，获得目前仅可能在基态分子上获得的活性激发态的详细动态信息。Kubarych教授的团队采用新颖的脉冲序列，结合了不同的光谱范围，如可见光和红外线，包括多个激光源，允许访问从飞秒到秒的时间尺度，将能够解开复杂的光循环，并利用2D-IR光谱的强大分辨率识别瞬态中间物质。随着低温能力的增加，该小组将获得光开关磁性分子和材料的合作超快动力学，他们将使用新的混合电子/振动光谱方法进行研究。该研究项目的长期目标是解决明确的社会需求，开发能源转换、储存和消除温室气体的新方法。这个项目的结果将通过阐明基本的设计原理来指导新的化学系统以及大分子结构的发展。Kubarych教授将利用对能源、技术和气候变化的广泛兴趣，通过为密歇根州东南部地区的中学生开发染料敏化太阳能电池的实际演示，吸引下一代女性和少数民族科学家。为了极大地扩大他的影响范围，他将制作视频和网络资源，描述太阳能转换的基本挑战，强调物理化学在开发新解决方案中的作用。

In this project funded by the Chemical Structure, Dynamics, and Mechanisms Program-A (CSDM-A) and the Chemical Instrumentation Program of Division of Chemistry, Professor Kevin J. Kubarych of the University of Michigan and his graduate and undergraduate students are addressing the fundamental relationships between structure, dynamics and function in molecules that, powered by light, are poised to dramatically reshape approaches to transforming carbon dioxide and to storing information. In both classes of system, photocatalysts for reduction of carbon dioxide, and photomagnets, the key chemical starting point involves molecules that have absorbed light, carrying out their initial functional steps in excited electronic states. Using novel experimental techniques based on ultrafast two-dimensional infrared (2D-IR) spectroscopy and related methods, Professor Kubarych and his group will obtain the level of detailed dynamical information on the active excited states that is presently only possible on ground state molecules. By employing novel pulse sequences that combine different spectral ranges such as the visible and infrared, including multiple laser sources permitting access to timescales ranging from femtoseconds to seconds, Professor Kubarych's team will be able to disentangle complex photocycles and identify transient intermediate species using the powerful resolution of 2D-IR spectroscopy. With the addition of low-temperature capabilities, the group will gain access to the cooperative ultrafast dynamics of photoswitchable magnetic molecules and materials, which they will examine using novel hybrid electronic/vibrational spectroscopy methods. The long term goal of this research project is to address the clear societal need to develop new approaches for energy conversion, storage, as well as the removal of greenhouse gases. Results of this project will guide development of new chemical systems as well as macromolecular constructs by elucidating the fundamental design principles. Professor Kubarych will leverage the widespread interest in energy, technology, and climate change to appeal to the next generation of women and minority scientists by developing hands-on demonstrations of dye-sensitized solar cells for middle and high school students in the southeast Michigan area. To dramatically broaden his reach, he will produce videos and a web resource describing basic challenges in solar energy conversion, highlighting the role of physical chemistry in the development of new solutions.