Attosecond Resolved Photoionization Studies of Atomic and Molecular Dynamics

原子和分子动力学的阿秒分辨光电离研究

• 批准号: 2208017
• 负责人: Joshua Williams
• 金额: $ 51.63万
• 依托单位: Board of Regents, NSHE, obo University of Nevada, Reno
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2208017&HistoricalAwards=false
• 关键词: Attosecond; Resolved; Photoionization; Studies; Atomic; Attosecond; Resolved; Photoionization; Studies; Atomic

In this project, physicists will attempt to measure what happens in an atom or molecule after a tightly bound electron is removed by a pulse of x-ray light, leaving the atom or molecule in an excited state which eventually decays to a lower energy configuration. The work will focus on a specific mode of decay (Auger decay) in which the excited atom or molecule ejects another (loosely bound) electron to carry away the excess energy. Here the Auger decay is expected to take around 100 attoseconds (0.0000000000000001 seconds). After Auger decay, a molecule will likely break up into pieces, leaving only its constituent atoms. The experimenters will try to measure this Auger decay time and correlate it with the type of fragments that are released, along with other measured quantities. This study will help illuminate our understanding of the quantum mechanical processes that play out during molecular breakup, and in particular our fundamental understanding of the Auger decay process. Additionally, it is expected that this will serve as the basis for at least one Ph.D. student’s dissertation, several undergraduate students' senior theses, and the employment and training of a postdoctoral fellow. This proposed experiment will attempt to measure the time-resolved dynamics of Auger decay in xenon, methyl iodide (CH3I), and expand our preliminary studies of dichloroethylene (C2H2Cl2). This experiment will employ the well-established COLd Target Recoil Ion Momentum Spectroscopy (COLTRIMS) technique to simultaneously determine the gas-phase molecular frame (i.e. molecular orientation in the laboratory frame), and the Auger decay time. Access to the timing information is achieved through the measurement of the electron momentum and knowledge of the time-dependent nature of the electric field. In this experiment the time-dependent electric field is supplied by the atomic or molecular system via the Auger decay. This experiment will expand our understanding of the dynamics involved in atomic and molecular systems following the ultrafast Auger decay. In the case of molecular systems, the experimenters will attempt to determine the correlation between the Auger decay timing and the Molecular Frame Angular Distribution (MFPAD). The MFPAD is highly sensitive to the molecular potential and at least in principle could be used to glean information about the molecular potential (i.e. the configuration of the molecule’s constituent atoms in space at the “moment” the photoelectron is ejected).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.

在这个项目中，物理学家将尝试测量在X射线光的脉冲紧密结合的电子后，将原子或分子中发生的事情测量，使原子或分子处于令人兴奋的状态，有时会衰减到较低的能量构型。这项工作将集中在特定的衰减模式（螺旋蛋白衰减）上，其中激发原子或分子弹出另一个（松散结合）的电子以携带多余的能量。在这里，预计螺旋螺旋腐烂将花费大约100秒（0.0000000000000001秒）。 螺旋螺旋腐烂后，分子可能会分解成碎片，仅留下其成分原子。实验者将尝试测量此螺旋螺旋的衰减时间，并将其与释放的片段类型以及其他测量量相关联。这项研究将有助于阐明我们对分子破裂过程中量子机械过程的理解，尤其是我们对螺旋螺旋衰减过程的基本理解。此外，预计这将是至少一位博士学位的基础。学生的论文，几位本科生的高级论文以及博士后研究员的就业和培训。该提出的实验将尝试测量Xenon，碘化甲基甲基（CH3I）的螺旋衰减的时间分辨动力学，并扩展我们对二氯乙烯（C2H2CL2）的初步研究。该实验将采用公认的冷靶后坐力离子动量光谱（Coltrims）技术，以同时确定气相分子框架（即实验室框架中的分子取向）和螺旋螺旋蛋白的衰减时间。通过测量电子动量和对电场时间相关性的知识，可以实现对时间信息的访问。在本实验中，原子或分子系统通过螺旋螺旋腐烂提供了时间依赖的电场。该实验将扩展我们对超快螺旋螺旋衰减后原子和分子系统涉及的动态的理解。在分子系统的情况下，实验者将尝试确定螺旋螺旋衰减时机与分子框架角分布（MFPAD）之间的相关性。 MFPAD对分子电位高度敏感，至少在原则上可以用来收集有关分子潜力的信息（即，在“时刻”中，分子在太空中的构成原子的构型被驱逐出来。这是NSF的法定任务，并通过评估范围来表现出良好的支持者的范围。