Excited State Dynamics

激发态动力学

• 批准号: RGPIN-2015-06730
• 负责人: Schuurman, Michael
• 金额: $ 2.55万
• 依托单位: University of Ottawa
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=664558
• 关键词: Excited; State; Dynamics

This program employs computational quantum chemical methods to reveal not only how molecules respond on femtosecond timescales to the absorption of a photon of light, but also how this dynamical response may be observed using time-resolved spectroscopic techniques.  Our approach utilizes trajectory simulations in which the time-evolution of the atomic and electronic degrees of freedom of molecules are determined by computing potential energy surfaces 'on-the-fly' using ab initio electronic structure methods.  However, molecular trajectories are not observable quantities; this requires that the molecular wave packet be probed using ultrafast laser pulses.  The ability of high-level simulation to predict the resulting time-resolved spectra unifies theoretical and experiment approaches to unravel the mechanistic details of ultrafast phenomena.  Our group is engaged with a wide network of experimental collaborators, in both academic ultrafast laser labs and advanced light source facilities, to investigate novel methods of interrogating molecular motions on inherent timescales.***The current proposal will employ a total of four NSERC supported students in three main research thrusts: 1) the development of model theories for molecular excited state dynamics, 2) the 'complete simulation' of time-resolved spectroscopic experiments, and 3) investigation of the potential for novel X-ray probes of molecular dynamics.  The first research thrust addresses a persistent gap in our understanding of excited state processes: the lack of descriptive theories and models for excited state processes.  The ultimate goal of running our "simulation machinery" on specifically chosen molecular examples and model systems is the construction of rules governing dynamics involving (conically) intersecting electronic surfaces. The second thrust recognizes that validation of dynamical methods require comparison to experimental results. The most unambiguous comparison to be made is via the direct simulation of experimental observables. Our group is uniquely positioned, both in the simulation toolkit we've developed and in the network of experimental collaborators we employ, to demonstrate the ability of theoretical methods to speak to modern ultrafast experiments.  Lastly, developments in light sources now allow for femtosecond X-ray pulses that may be deployed in ultrafast pump-probe experiments. The wavelengths of X-ray photons is on the order of interatomic distances and promise to yield location specific information on the electronic environment at particular atomic sites in a molecule.  Our aim is to guide the interpretation of these new experiments using our well-positioned techniques. This program will provide students with an opportunity to conduct leading-edge, multidisciplenary research within a global network of theoretical and experimental collaborators.**

该程序使用计算量子化学方法不仅揭示了分子如何在飞秒时间尺度上对光子的吸收做出反应，而且还揭示了如何使用时间分辨光谱技术来观察这种动态响应。我们的方法利用了轨迹模拟，其中分子的原子和电子自由度的时间演化是通过使用从头算电子结构方法计算势能面来确定的。然而，分子轨迹不是可观测的量；这需要使用超快激光脉冲来探测分子波包。高级模拟预测产生的时间分辨光谱的能力统一了理论和实验方法，以揭开超快现象的机制细节。我们的团队在学术超快激光实验室和先进的光源设备中与广泛的实验合作者网络合作，研究在固有时间尺度上询问分子运动的新方法。*当前的提议将在三个主要研究项目中使用NSERC支持的总共四名学生：1)分子激发态动力学模型理论的发展，2)时间分辨光谱实验的“完全模拟”，以及3)分子动力学新型X射线探测器的潜力的调查。第一个研究重点解决了我们对激发态过程理解中的一个持久的空白：缺乏关于激发态过程的描述性理论和模型。在特定选择的分子实例和模型系统上运行我们的“模拟机器”的最终目标是构建涉及(圆锥形)相交电子表面的动力学规则。第二个推力认识到，动力学方法的验证需要与实验结果进行比较。最明确的比较是通过实验观测数据的直接模拟。无论是在我们开发的模拟工具包中，还是在我们雇用的实验合作者网络中，我们的团队都处于独特的地位，以展示理论方法与现代超快实验对话的能力。最后，光源的发展现在允许在超快泵浦-探测器实验中部署飞秒X射线脉冲。X射线光子的波长是原子间距离的数量级，并有望提供关于分子中特定原子位置的电子环境的特定位置信息。我们的目标是使用我们定位良好的技术来指导对这些新实验的解释。该项目将为学生提供在理论和实验合作者的全球网络中进行前沿、多学科研究的机会。**