Collaborative Research: Understanding Ultrafast Observables

合作研究：理解超快可观测值

• 批准号: 2102066
• 负责人: Spiridoula Matsika
• 金额: $ 23.4万
• 依托单位: Temple University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2102066&HistoricalAwards=false
• 关键词: Collaborative; Research; Understanding; Ultrafast; Observables

With support from the Chemical Structure, Dynamics, and Mechanisms-A (CSDM-A) and Chemical Theory, Models, and Computational Methods (CTMC) programs in the Division of Chemistry, Professors Allison, Levine, and Weinacht at Stony Brook University, and Professor Matsika at Temple University are developing new ways to understand the information obtained from sophisticated measurements of the dynamics of molecules. The structure and behavior of molecules are governed by the rules of quantum mechanics. The field of quantum chemistry, which applies the principles of quantum mechanics to molecular problems, has developed over decades based on rigorous comparison between experiments and theory, resulting in reliable computer codes that can be used by non-experts to calculate the properties of molecules in their lowest-energy states. However, similar quantum chemistry calculations are far more challenging for molecules that have been excited, for example by absorbing energy from light, and are able to undergo very fast chemical transformations. Part of the difficulty in developing quantum chemistry methods for excited molecules is that the experimental measurements are much harder to interpret, and comparisons with theory are generally much less rigorous than for molecules in their ground state. This collaborative research team is working to better understand the experimental observables by studying molecules prepared in the same way using different types of experiments, and by making direct comparisons of those observables with quantum chemical calculations that simulate both the measurement process and the excited-state dynamics. In addition to producing a set of benchmark measurements for several representative molecules, the team is working toward a new paradigm for understanding measurements of the dynamics of molecules, including a new format for sharing data. Beyond these scientific broader impacts, the project also provides advanced training for graduate students in a highly collaborative environment.Ultrafast spectroscopy offers the opportunity to directly probe the dynamics of molecules after excitation. However, the interpretation of data from ultrafast spectroscopy remains a challenge because projection of high dimensional dynamics into a much lower dimensional signal is unavoidable. In principle, a probe that projects the time-dependent molecular wave packet onto the set of all possible states provides a complete, if difficult to interpret, picture of the dynamics in question. The research team led by Professors Allison, Levine, Weinacht, and Matsika is addressing this problem by applying multiple recently developed experimental and theoretical tools to measure and calculate the dynamics of identically prepared gas-phase molecules. Complementary time-resolved photoelectron and visible transient absorption probes project the molecular wave packet onto a broad swath of Hilbert space, providing more information about the dynamics than is possible with either method on its own. The measurements are compared with ab initio simulations of the dynamics, from which identical projections are performed. This rigorous comparison between measured and calculated spectra utilizing complementary probes is enabled by recent methodological advances, including the development of a gas-phase transient absorption spectrometer and novel ab initio tools for efficiently computing probe signals from large molecular dynamics data sets. These systematic studies are producing benchmark datasets on archetypal molecular systems that present challenging problems at the vanguard of quantum chemistry and molecular dynamics, including non-adiabatic dynamics and intersystem crossing. The fundamental processes under investigation play an important role across a wide range of chemical reactions that are driven by light. Through this collaborative effort, the team is also working to develop and disseminate a new data format for sharing both theoretical and experimental ultrafast dynamics results based on the FAIR principle (findable, accessible, interoperable, reusable). Graduate students working on the project learn how to approach complex problems in chemistry based on collaborative research at the forefront of both experiment and theory.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.

在化学结构，动力学和机制的支持下 - A（CSDM-A）以及化学理论，模型和计算方法（CTMC）在化学划分中，Stony Brook University的Allison，Levine和Weinacht教授，Temple University的Matsika教授在Temple University的Matsika教授正在开发新的方法，从而从成熟的量表中获得了新的信息，该方法是从成熟的测量中获得的。分子的结构和行为受量子力学规则控制。将量子力学原理应用于分子问题的量子化学领域，基于实验和理论之间的严格比较，已经开发了数十年，从而产生了可靠的计算机代码，这些计算机代码可由非专家使用，以计算其最低能量状态中分子的性质。但是，对于那些受到激发的分子，例如通过吸收光中的能量并能够进行非常快速的化学转化，类似的量子化学计算更具挑战性。开发激发分子的量子化学方法的一部分困难是，实验测量很难解释，并且与理论的比较通常不如其基态分子的严格性要严格得多。这个协作研究团队正在努力通过使用不同类型的实验来研究以相同方式制备的分子，并通过对这些可观察到的量子化学计算进行直接比较，以模拟测量过程和激发态动力学。除了为几个代表性分子生产一组基准测量外，该团队还致力于一种新的范式，以了解分子动力学的测量，包括用于共享数据的新格式。除了这些科学的更广泛的影响外，该项目还为研究生提供了高度协作环境的高级培训。UltrafastSpectroscopy提供了机会，可以在激发后直接探测分子的动态。但是，从超快光谱法的数据解释仍然是一个挑战，因为不可避免地将高维动力学投影到较低的维信号中。原则上，将时间依赖的分子波数据包投放到所有可能状态的集合的探测器提供了一个完整的，即使难以解释的情况，即所讨论的动力学图片。由Allison，Levine，Weinacht和Matsika教授领导的研究团队通过应用多种最近开发的实验和理论工具来测量和计算相同制备的气相分子的动态，从而解决了这一问题。互补的时间分辨光电子和可见的瞬态吸收探针将分子波数据包投射到宽阔的希尔伯特空间上，提供了有关动力学的更多信息，而不是单独使用任何一种方法。将测量结果与对动力学的摘要模拟进行了比较，该动力学进行了相同的投影。最近的方法学进展可以实现使用互补探针的测量光谱和计算的光谱之间的严格比较，包括开发气相瞬态吸收光谱仪和新型的AB InitiO工具，以有效地计算出大型分子动力学数据集的探针信号。这些系统的研究正在对原型分子系统产生基准数据集，这些数据集在量子化学和分子动力学（包括非绝热动力学和系统间交叉）中提出了具有挑战性的问题。在调查中的基本过程在由光驱动的广泛的化学反应中起着重要作用。通过这项协作工作，团队还致力于开发和传播新的数据格式，以基于公平原则（可找到，可访问，可互操作，可重复使用）共享理论和实验性超快动态结果。从事该项目的研究生学习如何基于实验和理论的最前沿的协作研究来解决化学问题的复杂问题。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子和更广泛影响的评估评估的评估来支持的。