Correlating Electronic and Atomic Motions in Photoinduced Electron-Proton Transfer Reactions with Two-Dimensional Electronic-Vibrational and X-ray Spectroscopies

在这个由化学系化学结构与动力学a项目资助的项目中，华盛顿大学的Munira Khalil教授正在开发一种微观描述，描述氢原子在吸收光后如何从供体转移到受体。为了应对这一实验挑战，新的光谱方法能够直接测量电子和原子运动的耦合，从红外（IR）到x射线的电磁波谱被开发出来。哈利勒教授开发的外展项目包括为来自stem弱势背景的中学女生提供一个动手光学模块，这是一个独特的“女孩参与科学”项目，通过华盛顿大学伯克博物馆开展。这项工作的更广泛的影响包括在实验室、同步加速器和自由电子激光源的最先进的超快技术方面培训下一代科学家，创造新的飞秒技术，并增加对光诱导电子-质子转移过程的理解。本研究采用双管齐下的实验方法，有两个主要目标。第一个是开发新的二维飞秒电子和红外光谱（2D EV）的使用，使用两个紫外（UV）脉冲序列，然后是宽带中红外脉冲。这将使该小组能够直接测量在模型分子内和分子间氢键配合物中光诱导耦合电子-质子转移的耦合电子电荷密度和氢原子的运动。第二个重点是利用超快x射线吸收和共振非弹性x射线散射（RIXS）光谱直接监测氢键供体和受体原子周围的电荷分布。平衡x射线实验在先进光源（ALS）上进行，超快RIXS实验在直线相干光源（LCLS）上进行。光致电子-质子转移是许多自然和人工能量转换过程中的中心反应。未来可能的影响包括用于替代能源生产的新分子、材料和设备的发展。

In this project funded by the Chemical Structure and Dynamics-A program of the Chemistry Division, Professor Munira Khalil of the University of Washington is developing a microscopic description of how a hydrogen atoms move from a donor to an acceptor following the absorption of light. To meet this experimental challenge, new spectroscopic methods capable of directly measuring the coupling of electronic and atomic motions are developed spanning the electromagnetic spectrum from the infrared (IR) to X-rays. An outreach program developed by Professor Khalil includes a hands-on optics module for middle school girls from STEM-disadvantaged backgrounds in a unique "Girls on Science" program run through the University of Washington's Burke Museum. The broader impacts of this work include training the next generation of scientists in state-of-the-art ultrafast techniques in the laboratory and at synchrotrons and free electron laser sources, creating new femtosecond technologies, and an increased understanding of the photo-induced electron-proton transfer process. This research has two main objectives with a two-pronged experimental approach. The first is to develop the use of novel two-dimensional femtosecond electronic and infrared spectroscopy (2D EV) using a train of two ultraviolet (UV) pulses followed by a broadband mid IR pulse. This will enable the group to directly measure the coupled electronic charge density and the movement of the hydrogen atom in photo-induced coupled electron-proton transfer in model intra and inter-molecular hydrogen bonded complexes. The second thrust is using ultrafast X-ray absorption and Resonant Inelastic X-ray scattering (RIXS) spectroscopy to directly monitor the charge distribution around the hydrogen bond donor and acceptor atoms. The equilibrium X-ray experiments are being conducted at the Advanced Light Source (ALS) and the ultrafast RIXS experiments are conducted at the Linac Coherent Light Source (LCLS). Photo-induced electron-proton transfer is a central reaction in several natural and artificial energy conversion processes. Possible future impacts include the development of new molecules, materials and devices for alternative energy production.