CAREER: Tabletop Extreme Ultraviolet Spectroscopy of Femtosecond Spin Crossover Dynamics

有了这个奖项，化学系的化学结构，动力学和机制（CSDM-A）计划正在资助伊利诺伊大学厄巴纳-香槟分校（UIUC）的约书亚Vura-Weis教授，以研究电子自旋状态变化的光诱导过程的机制。 在某些铁和铁钴络合物吸收可见光后，它们经历快速重排（自旋翻转）并被困在可能对实际应用有用的长寿命状态中。在这个项目中使用的实验技术是桌面极紫外（XUV）光谱。 两个旨在促进深入和持续的本科生参与光谱学研究的研讨会与国际分子光谱学研讨会（ISMS）在UIUC建立。为期一周的“雪中光谱学”冬季强化课程为学生提供了物理化学研究所需的基础知识，并使他们能够提前一年在家乡机构开始高水平的工作。 为期两天的ISMS本科生预会议，类似于戈登研究研讨会系列研究生，建立了一个年轻的研究人员社区，并提高了本科生在主要会议上的演讲水平。在这个建议中所展示的新的光谱方法是适用于广泛的物理和无机化学问题，从太阳能电池的设计，在飞秒分辨率的极紫外（XUV）瞬态吸收光谱是用来解决的自旋弛豫过程中的一系列过渡金属配合物的细节。Vura-Weis小组进一步扩展了其测量自旋交叉期间振动动力学的能力。电子转移和自旋动力学之间的相互作用是含开壳层过渡金属配合物的物理和反应性的关键因素。Vura-Weis小组使用XUV瞬态吸收的自旋状态特异性和飞秒时间分辨率来测量铁多吡啶复合物的弛豫级联，特别关注短寿命金属中心三重态的潜在作用。普鲁士蓝中的电子转移和自旋交叉之间的相互作用正在一系列离散的氰基桥接的铁钴系统中测量。在这种情况下，XUV吸收的元素特异性允许独立探测每种金属的动力学。 门电子动力学的特定分子运动的元素特定的XUV脉冲相干振动光谱确定。 为了使本科生更容易获得物理化学的研究，在伊利诺伊大学厄巴纳-香槟分校举办了一个关于光谱学的冬季学校，与国际分子光谱学研讨会（ISMS）有关。 此外，本次会议前为期两天的本科生会议发展了一个支持年轻研究人员的社区。

With this award, the Chemical Structure, Dynamics and Mechanisms (CSDM-A) Program of the Division of Chemistry is funding Professor Joshua Vura-Weis at the University of Illinois at Urbana-Champaign (UIUC) to investigate the mechanism of light-induced processes where the electronic spin state changes. After certain iron and iron-cobalt complexes absorb visible light, they undergo a rapid rearrangement (spin flip) and become trapped in a long-lived state that may be useful for practical applications. The experimental technique used in this project is tabletop extreme ultraviolet (XUV) spectroscopy. Two workshops designed to foster deep and sustained undergraduate engagement in spectroscopy research are established in association with the International Symposium on Molecular Spectroscopy (ISMS) at UIUC. A weeklong "Spectroscopy in the Snow" intensive winter course gives sophomores the foundational knowledge required for physical chemistry research and allows them to begin high-level work in their home institutions one year ahead of schedule. A two-day ISMS pre-conference for undergraduates, analogous to the Gordon Research Seminar series for graduate students, builds a community of young researchers and raises the level of undergraduate presentations at the main conference. The new spectroscopic methods demonstrated in this proposal are applicable for a wide range of problems in physical and inorganic chemistry, from photocatalysis to solar cell design.Extreme ultraviolet (XUV) transient absorption spectroscopy at femtosecond resolution is used to resolve the details of the spin relaxation process in a series of transition metal complexes. The Vura-Weis group further extends its capabilities to measure vibrational dynamics during the spin crossover. The interplay between electron transfer and spin dynamics is a key factor in the photophysics and reactivity of complexes containing open-shell transition metals. The Vura-Weis group uses the spin-state specificity and femtosecond time resolution of XUV transient absorption to measure the relaxation cascade of iron polypyridyl complexes, specifically focusing on the potential role of a short-lived metal-centered triplet state. The interplay between electron transfer and spin crossover in Prussian Blues is being measured in a series of discrete cyano-bridged iron-cobalt systems. In this case, the element specificity of XUV absorption allows the dynamics of each metal to be independently probed. The particular molecular motions that gate the electron dynamics are identified by element-specific XUV impulsive coherent vibrational spectroscopy. To make research in physical chemistry more accessible to undergraduates, a winter school on spectroscopy takes place at the University of Illinois, Urbana-Champaign, in connection with the International Symposium on Molecular Spectroscopy (ISMS). In addition, a two-day undergraduate meeting preceding this conference develops a supportive community of young researchers.