Collaborative Research: Probing Attosecond Charge Dynamics in Atoms and Molecules

合作研究：探测原子和分子中的阿秒电荷动力学

• 批准号: 1806575
• 负责人: Zenghu Chang
• 金额: $ 21万
• 依托单位: The University of Central Florida Board of Trustees
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-01 至 2022-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1806575&HistoricalAwards=false
• 关键词: Collaborative; Research; Probing; Attosecond; Charge

An ability to identify, tag and follow unambiguously quantum trajectories of electrons in molecular systems is central to addressing questions that are key to unlocking solutions to an array of contemporary scientific and technical challenges - understanding the chemistry of interstellar media, reducing our carbon footprint, enabling efficient, clean energy sources and controlling dynamics in biological molecules are just a few examples. Light-induced charge dynamics, for example, is ubiquitous in catalysis, photosynthesis, the photovoltaic effect, radiation damage in biomolecules and atmospheric chemistry. With clock speeds of order 1 femtosecond (10^-15 s), the energy flow and correlated dance between electrons and atomic nuclei require subfemtosecond temporal resolution (e.g., 100 attosecond = 0.1 femtosecond) and carefully-designed experimental techniques to track reliably. The University of Central Florida (UCF) - University of Maryland (UMD) collaboration has assembled the instrumentation and personnel to study such dynamics in important prototype molecules. Specifically, charge dynamics will be probed experimentally by transient changes in the absorption spectrum of so-called core-level states (those closest to the nucleus) of the carbon atom. These novel measurements may lead to new understanding of key physical concepts, clearer pictures of fundamental processes and novel ways to control electron dynamics. Employing a few-cycle infrared intense (IR) pump and an attosecond soft X-ray probe in the water window (240 to 330 eV in this study) for transient absorption of core-level carbon atoms, the University of Central Florida (UCF) - University of Maryland (UMD) collaboration is investigating ultrafast dynamics in two important hydrocarbons. One set of experiments is dedicated to tracking structural changes induced by the IR pulse in methane as it loses hydrogen atoms (deprotonization) with subfemtosecond temporal resolution. The second study focuses on IR-induced isomerization of acetylene into vinilydene also with subfemtosecond resolution. One novelty of these studies rests in a forty-fold improvement in temporal resolution over previous transient absorption measurements in the water window. The UCF-UMD collaboration is ideally suited to carry out this investigation because of the investigators' long history in building and operating state-of-the-art attosecond lasers (UCF) and probing and controlling atomic and molecular dynamics (UMD). To ensure the best interpretation of the experimental results, the team works closely with UCF theorists running contemporary numerical codes such as XCHEM and MESA to help analyze the data. The results will provide new insight into time-dependent structure changes and correlated electron motion induced by strong external perturbation, which potentially could reveal innovative ways to control electron dynamics.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.

在分子系统中识别，标记和遵循明确量化电子轨迹的能力是解决问题的关键问题，这些问题是为一系列当代科学和技术挑战解锁解决方案的关键 - 理解星际媒体的化学反应，减少我们的碳足迹，使我们的碳足迹有效，清洁能源，清​​洁，清洁，清洁能源和控制动力学的动力学。 例如，光诱导的电荷动力学在催化，光合作用，光伏效应，生物分子的辐射损伤和大气化学中无处不在。凭借阶的时钟速度为1 femtosecond（10^-15 s），电子和原子核之间的能量和相关的舞蹈需要次秒的时间分辨率（例如100个attosecond = 0.1 promtosecond）和精心设计的实验技术来跟踪关联。 佛罗里达州中部大学（UCF） - 马里兰州大学（UMD）合作组织了仪器和人员，以研究重要的原型分子中的这种动态。 具体而言，将通过碳原子的所谓核心水平状态（最接近原子核）的吸收光谱的瞬时变化对电荷动力学进行实验探测。这些新颖的测量可能会导致对关键物理概念的新理解，基本过程的更清晰图片以及控制电子动力学的新方法。 在水窗中使用几个周期的红外强度（IR）泵和一个柔软的X射线探测器（本研究中的240至330 eV），用于短暂吸收核心水平碳原子，中央佛罗里达大学（UCF） - 马里兰州大学（UMD）（UMD）（UMD）研究了两个重要的Hyledrocarbons的超级动力学。 一组实验致力于跟踪甲烷中IR脉冲引起的结构变化，因为它以次秒时间分辨率失去氢原子（去质子化）。第二项研究的重点是通过亚速度分辨率的IR诱导的乙炔异构化以及乙烯烯的异构化。 这些研究的一种新颖性在于，时间分辨率比以前的瞬时吸收测量值改善了。 由于研究人员在建造和运行最先进的attsecond激光器（UCF）以及探测和控制原子和分子动力学（UMD）方面的悠久历史，因此，UCF-UMD协作非常适合进行这项调查。 为了确保对实验结果的最佳解释，团队与运行当代数值代码（例如Xchem和Mesa）的UCF理论家紧密合作，以帮助分析数据。 结果将为时间依赖的结构变化和相关的电子运动提供新的见解，这可能会揭示控制电子动力学的创新方法。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审查标准来通过评估来通过评估来支持的。

项目成果

Generation of few-cycle multi-millijoule 2.5 μm pulses from a single-stage Cr2+:ZnSe amplifier

从单级 Cr2 :ZnSe 放大器生成几个周期的多毫焦耳 2.5 μm 脉冲

• DOI: 10.1038/s41598-020-64330-8
• 发表时间: 2020
• 期刊: Scientific Reports
• 影响因子: 4.6
• 作者: Wu, Yi;Zhou, Fangjie;Larsen, Esben W.;Zhuang, Fengjiang;Yin, Yanchun;Chang, Zenghu
• 通讯作者: Chang, Zenghu

Signal Retrieval With Measurement System Knowledge Using Variational Generative Model

使用变分生成模型利用测量系统知识进行信号检索

• DOI: 10.1109/access.2020.2978435
• 发表时间: 2020
• 期刊: IEEE Access
• 影响因子: 3.9
• 作者: Zhu, Zheyuan;Sun, Yangyang;White, Jonathon;Chang, Zenghu;Pang, Shuo
• 通讯作者: Pang, Shuo

Attosecond science based on high harmonic generation from gases and solids

• DOI: 10.1038/s41467-020-16480-6
• 发表时间: 2020-06-02
• 期刊: NATURE COMMUNICATIONS
• 影响因子: 16.6
• 作者: Li, Jie;Lu, Jian;Chang, Zenghu
• 通讯作者: Chang, Zenghu

Attosecond chirp compensation in water window by plasma dispersion

• DOI: 10.1364/oe.26.033238
• 发表时间: 2018-12-10
• 期刊: OPTICS EXPRESS
• 影响因子: 3.8
• 作者: Chang, Zenghu

Enhancement of gain and efficiency of an Ho:YLF energy booster through deep thermoelectric cooling

通过深度热电冷却提高 Ho:YLF 能量增强器的增益和效率

• DOI: 10.1364/optcon.456612
• 发表时间: 2022
• 期刊: Optics Continuum
• 作者: Zhou, Fangjie;Cintron, Adrian;Wu, Yi;Chang, Zenghu
• 通讯作者: Chang, Zenghu