|Date||April 12, 2019||Time||3:35 - 5:00 pm|
|Location||Baylor Sciences Building, Room E.125|
Md Kazi Rokunuzzaman
Light-Emitting Halide Perovskite Nanoantennas
Hybrid halide perovskites materials are a class of dielectric have distinct opto-electronic properties such as high refractive index, exhibit excitonic states at room temperature, chemically tunable bandgap, high defect tolerance and quantum yield of luminesce. On other hand, Nanoantenna made of high-index dielectrics with low losses in visible and infrared ranges have emerged as a novel platform for advanced nanophotonic devices. In this talk, I am going to present a work of E.Y. Tiguntseva et.al. In this work for the first time they have used perovskite material to create nanoantennas. They have fabricated perovskite nanoparticles supporting electric and magnetic dipolar and multipolar Mie resonance to create light-emitting nanoantennas with enhanced photoluminescence. Moreover, they have also showed halide perovskite nanoantennas can emit light in the range of 530-770 nm. For the fabrication of perovsktite materials this research group used laser ablation-based technique of thin films prepared by wet-chemistry as a novel cost-effective approach.
Similarity of Fast and Slow Earthquakes Illuminated by Machine Learning
Tectonic faults fail in a spectrum of modes, ranging from earthquakes to slow slip events. In this talk, I would discuss the paper where laboratory earthquakes are conducted and shows that both slow and fast slip modes are preceded by a cascade of micro-failure events that radiate elastic energy in a manner that foretells catastrophic failure. Using machine learning, the authors find that acoustic emissions generated during shear of quartz fault gouge under normal stress predict the timing and duration of laboratory earthquakes. Laboratory slow earthquakes reach peak slip velocities of the order of 1 × 10−4 m /s and do not radiate high-frequency elastic energy, consistent with tectonic slow slip. Acoustic signals generated in the early stages of impending fast laboratory earthquakes are systematically larger than those for slow slip events. It shows that a broad range of stick–slip and creep–slip modes of failure can be predicted and share common mechanisms, which suggests that catastrophic earthquake failure may be preceded by an organized, potentially forecastable, set of processes.
|Publisher||Department of Physics|
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