Colloidal Quantum dots (QDs) have garnered considerable scientific and technological interest as a promising material for next generation solar cells, photo-detectors, lasers, bright light-emitting diodes (LEDs), and reliable biomarkers. However, for practical realization of these applications, it is crucial to understand the complex photo-physics of QDs that are very sensitive to surface chemistry and chemical surroundings. Depending on the excitation density, QDs can support single or multiple excitations. The first part of this talk addresses evolution of QD excited state dynamics in the regime of low excitation intensity. We use temperature-resolved time-resolved fluorescence spectroscopy to study exciton dynamics from picoseconds to microseconds and use kinetic modeling based on classical electron transfer to show...
With increased availability and growing commercial applications, aluminum-based metal matrix composites show promise as high specific strength structural materials. Before they can be implemented however, they require thorough characterization and testing. A novel nanostructured aluminum-based metal matrix composite (MMC) was characterized through a combination of microstructural analysis and mechanical testing. Two composites were studied, an aluminum MMC reinforced with 50 nm boron carbide, (B4C) and an aluminum MMC reinforced with 500 nm boron carbide. Transmission electron microscopy (TEM) analysis revealed an ultra-fine grained matrix with grains on the order of 100 – 300 nm. The quasi-static and dynamic response of the composites was compared with the behavior of...
“BROADBAND TERAHERTZ CONDUCTIVITY AND OPTICAL TRANSMISSION OF INDIUM-TIN-OXIDE (ITO) NANOMATERIALS”
EVENT DATE: Tuesday, October 1, 2013
LUNCH WITH THE SPEAKER : 11:30am – 12:30pm * 238 Grigg
SEMINAR - 12:45 - 1:45pm * 132 Grigg
Time-domain terahertz spectroscopy (THz-TDS) provides a non-contact method for characterizing the electrical and dielectric properties of technologically important materials, e.g., transparent and conducting Indium Tin Oxide (ITO) thin films, which are widely used in optoelectronic devices. Recently, ITO nanomaterials have attracted a lot of attention, because of its omidirectional and wideband anti-reflection characteristics. Indium-tin-oxide (ITO) nanorods (NRs) and nanowhiskers (NWhs) were fabricated by an electron-beam glancing-angle deposition (GLAD) system. Two terahertz (THz) time-domain spectrometers (TDS) with combined spectral coverage from 0.15 to 9.00 THz were used. These allow accurate determination of the optical and electrical properties of such ITO nanomaterials in the frequency range from 0.20 to 4.00 THz...Read More