Thursday, November 15, 2018

Presentation Prof. Keith Nelson-"Using light to study materials: Thermal, acoustic, shock, and particle impact responses driven and monitored by light"

 Tuesday, November 27, 2018 at 11:45am to 1:00pm
 3-370
Applied Physics @ MIT presents a lecture.
Prof. Keith Nelson, MIT Chemistry
"Using light to study materials: Thermal, acoustic, shock, and particle impact responses driven and monitored by light"
Much of materials science and engineering is moved forward by new methods for measurement of material properties. In many cases, materials are poked and prodded on various length and time scales in order to measure their mechanical responses, electrical and thermal conductivities, and other characteristics. We will review methods that use light to measure material properties, in some cases avoiding poking and prodding entirely (no physical contact with the sample) and in other cases initiating physical contact with experimental control that is otherwise difficult to achieve. We’ll start with a brief, wide-ranging overview of some recently developed methods for material measurement including the use of far-infrared (terahertz-frequency) light to move electrons and ions in ways that lead to new crystalline phases and the use of ultrashort x-ray pulses to monitor dynamical changes in crystal structure directly through time-resolved x-ray diffraction. Then we’ll focus on measurements of thermal and mechanical behavior of materials, with a wide range of practical applications including some already realized commercially. Much of the research is collaborative between Course 5 and Courses 2, 3, 6, 8, 10, 16, and 22, including measurements of thermal transport in materials of interest for thermoelectrics, nanoelectronics, and fusion reactor applications; measurements of laser-induced acoustic waves that reveal polymer viscoelastic properties, microelectronics thin film dimensions, and acoustic phonon contributions to thermal transport; measurements of laser-driven shock waves that reveal stress-induced crystal fracture dynamics and energetic material chemical initiation; and laser-launched microparticle impact measurements that permit direct observation of the elementary processes in some types of additive manufacturing. The research illustrates the interdisciplinary manner in which optics and spectroscopy methods developed in physical chemistry are applied to materials of wide-ranging fundamental and practical interest.

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