Professor Minnich Receives IPPA Junior Prize
Austin Minnich, Professor of Mechanical Engineering and Applied Physics, is a recipient of the International Photothermal and Photoacoustics Association (IPPA) Junior Prize. He received the prize for outstanding contributions to the understanding of quasiballistic thermal transport, including the development of photothermal methods to directly probe heat conduction at length scales comparable to phonon mean free paths; for demonstrating how microscopic transport properties of thermal phonons in solids may be obtained using photothermal experimental methods along with ab-initio calculations; and for advances in the mathematical treatment of quasiballistic transport using the Boltzmann equation.
Andrei Faraon, Assistant Professor of Applied Physics and Materials Science, and colleagues have discovered how to use computer-chip manufacturing technologies to create the kind of reflective materials that make safety vests, running shoes, and road signs appear shiny in the dark. The new technology uses surfaces covered by a metamaterial consisting of millions of silicon pillars, each only a few hundred nanometers tall. By adjusting the size of the pillars and the spacing between them, Faraon can manipulate how the surface reflects, refracts, or transmits light. [Caltech story]
"Hot" Electrons Move Faster Than Expected
For the first time, Marco Bernardi, Assistant Professor of Applied Physics and Materials Science, and colleagues have been able to directly observe the ultrafast motion of electrons immediately after they are excited with a laser—and found that these electrons diffuse into their surroundings much faster and farther than previously expected. "Our work shows the existence of a fast transient that lasts for a few hundred picoseconds, during which electrons move much faster than their room-temperature speed, implying that they can cover longer distances in a given time when manipulated with lasers," says Professor Bernardi. "This non-equilibrium behavior could be employed in novel electronic, optoelectronic, and renewable energy devices, as well as to uncover new fundamental physics." [Caltech story]