Development of an Ultrafast Laser Instrument for Creating and Probing Matter under Extreme Pressures, Temperatures, and Strain Rates

技术总结：极端条件下材料行为的知识在许多科学领域都是有价值的，包括材料工程、能源和国防技术、反应化学、环境和行星科学。然而，目前可用于金刚石砧细胞高压静态实验的实验工具在绝大多数情况下只能提供关于时间平均特性的信息，而在微观水平上关于超快现象的动态信息则缺失。这项工作的目标是开发一种新的仪器，它结合了高静压和动态加载（例如，通过冲击和/或热波）的条件，并使用超快（飞至皮秒）脉冲激光干涉和光谱技术，在这些条件下原位探测材料的特性，并具有适当的微观空间分辨率。随着该仪器的发展，金刚石砧细胞中材料的研究将扩展到10,000 K以上的温度和100 GPa以上的压力。此外，在超短时间尺度（40秒到每秒）上观察物理和化学现象，与快速相变和基本化学反应的时间相当，将成为可能。这种新方法有可能揭示具有独特性质的新材料的形成，并导致发现新的相变和化学反应性，以及推进我们对地球和行星内部的理解。该仪器将提供给合作者，以及来自nsf支持的项目的独立用户，如compes和卡内基暑期实习生项目，以及总部位于卡内基的美国能源部支持的CDAC高压中心。该地区的高中生、本科生和研究生，包括与卡内基有积极合作的当地黑人霍华德大学的学生，将受益于参与拟议仪器的开发和用它进行的科学研究所提供的科学培训。外行人总结：在极端条件下（高压和高温）对材料的研究对于寻找新材料和更好地理解地球和其他行星的成分和过程是有用的。然而，目前这些研究中有许多缺乏实验速度来研究原子和电子水平上的非常快的现象，例如化学反应和向新材料相的转变。该项目旨在开发一种新的仪器，该仪器将通过明亮激光脉冲（长度为百万分之一秒或更短）的快速加热和压缩来创造极端条件，并在这些快速变化的条件下测量材料的物理和化学性质。该仪器有可能在这些现象的自然时间尺度上观察材料的新行为，如结构和化学成分的快速变化。由于这种新仪器的独特条件，可以发现具有非凡性质的新材料和化合物，并将实现对地球和行星内部的深入了解。该仪器将提供给合作者，以及来自美国国家科学基金会支持的项目（如compes和卡内基暑期实习生项目）的独立用户，以及总部位于卡内基的美国能源部支持的CDAC高压中心。该地区的高中生、本科生和研究生，包括与卡内基有积极合作的当地黑人霍华德大学的学生，将受益于参与拟议仪器的开发和用它进行的科学研究所提供的科学培训。

Technical summary: Knowledge of the behavior of materials under extreme conditions is valuable in many fields of science, including materials engineering, energy and defense technologies, reaction chemistry, and environmental and planetary sciences. However, currently available experimental tools for high-pressure static experiments in diamond anvils cells in a vast majority of cases provide only information about time-averaged properties, and dynamical information about ultrafast phenomena at the microscopic level is missing. The goal of the work is to develop a new instrument which combines conditions of high static pressure with dynamic loading (e.g., by shock and/or thermal waves) and probes materials properties in situ under these conditions using ultrafast (femto- to picosecond) pulsed laser interferometric and spectroscopic techniques with the appropriate microscopic spatial resolution. With the development of this instrumentation, studies of materials in the diamond anvil cell will be extended to temperatures beyond 10,000 K at pressures beyond 100 GPa. Moreover, observations of physical and chemical phenomena on ultra-short time scales (40 fs to ps), comparable to times of fast phase transformations and elementary chemical reactions, will be enabled. This new approach has the potential to reveal the formation of new materials with unique properties and lead to the discovery of new phase transformations and chemical reactivity, as well as advancing our understanding of the Earth and planetary interiors. The instrument will become available for collaborators, and to independent users from NSF-supported programs such as COMPRES and the Carnegie Summer Intern Program, as well as from the DOE-supported CDAC high-pressure center, headquartered at Carnegie. Area high school students, undergraduates and graduate students, including those from local historically-black Howard University with whom Carnegie has an active collaboration, will benefit from the scientific training provided by participation in the development of the proposed instrument and the scientific studies conducted with it. Layman summary: Studies of materials under extreme conditions (high pressure and temperature) can be useful in the search for new materials and for better understanding the compositions and processes in the Earth and other planets. However, many of these studies currently lack the experimental speed to study very fast phenomena on the level of atoms and electrons, such as chemical reactions and transformations to new material phases. This project is aimed at developing a new instrument which would create extreme conditions through rapid heating and compression with bright laser pulses (1 millionth of 1 millionth of a second in length or less), and measure materials physical and chemical properties under these rapidly-changing conditions. This instrument has the potential to observe new behaviors in materials such as rapid changes in structure and chemical composition on the natural time scales of these phenomena. Due to the unique nature of the conditions available for this new instrument, new materials and chemical compounds with extraordinary properties can be discovered, and advanced understanding of the Earth and planetary interiors will be achieved. The proposed instrument will become available for collaborators, and to independent users from NSF-supported programs such as COMPRES and the Carnegie Summer Intern Program, as well as from the DOE-supported CDAC high-pressure center, headquartered at Carnegie. Area high school students, undergraduates and graduate students, including those from local historically-black Howard University with whom Carnegie has an active collaboration, will benefit from the scientific training provided by participation in the development of the proposed instrument and the scientific studies conducted with it.