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

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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.