208 research outputs found

    Viscoelastic optical nonlocality of low-loss epsilon-near-zero nanofilms

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    Optical nonlocalities are elusive and hardly observable in traditional plasmonic materials like noble and alkali metals. Here we report experimental observation of viscoelastic nonlocalities in the infrared optical response of doped cadmium-oxide, epsilon-near-zero nanofilms. The nonlocality is detectable thanks to the low damping rate of conduction electrons and the virtual absence of interband transitions at infrared wavelengths. We describe the motion of conduction electrons using a hydrodynamic model for a viscoelastic fluid, and find excellent agreement with experimental results. The electrons elasticity blue-shifts the infrared plasmonic resonance associated with the main epsilon-near-zero mode, and triggers the onset of higher-order resonances due to the excitation of electron-pressure modes above the bulk plasma frequency. We also provide evidence of the existence of nonlocal damping, i.e., viscosity, in the motion of optically-excited conduction electrons using a combination of spectroscopic ellipsometry data and predictions based on the viscoelastic hydrodynamic model.Comment: 19 pages, 5 figure

    Long-lived modulation of plasmonic absorption by ballistic thermal injection

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    Energy and charge transfer across metal-semiconductor interfaces are the fundamental driving forces for a broad range of applications, such as computing, energy harvesting, and photodetection. However, the exact roles and physical separation of these two phenomena remains unclear, particularly in plasmonically-excited systems or cases of strong nonequilibrium. We report on a series of ultrafast plasmonic measurements that provide a direct measure of electronic distributions, both spatially and temporally, following optical excitation of a metal-semiconductor heterostructure. For the first time, we explicitly show that in cases of strong non-equilibrium, a novel energy transduction mechanism arises at the metal/semiconductor interface. We find that hot electrons in the metal contact transfer their energy to pre-existing electrons in the semiconductor, without transfer of charge. These experimental results findings are well-supported by both rigorous multilayer optical modeling and first-principle, ab initio calculations

    Public Health and Disasters: An Emerging Translational and Implementation Science, Not “Lessons Learned”

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    Disaster Medicine is a relatively new multidisciplinary field of science with clear public health implications as it focuses on improving outcomes for populations rather than for individual patients. As with any other scientific discipline, the goal of public health and disaster research is to create new knowledge and transfer evidence-based data to improve public health. The phrase "lessons learned" has crept into the disaster lexicon but must be permanently erased as it has no place in the scientific method. The second edition of Koenig and Schultz's Disaster Medicine: Comprehensive Principles & Practice adds to the growing knowledge base of this emerging specialty and explains why "lessons learned" should be discarded from the associated vocabulary. (Disaster Med Public Health Preparedness. 2017;11:610-611)

    The effect of hull form and weight distribution on structural loading.

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    http://archive.org/details/effectofhullform02run
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