SGER: Quantum Electronic Properties of Ultraviolet Laser Phosphors

这个项目研究了稀土离子掺杂的氧化物纳米晶强散射粉末的全新的量子光学性质。无镜激光发射是在强多次散射区用能量范围为1-10keV的电子激发而产生的。通过火焰喷洒醇盐前驱体，合成了含有紫外线发射离子的氧化铝纳米晶粉末，该工艺获得了良好的颗粒均匀度、大小可控和高纯度。使用可溶金属有机前驱体制备的未团聚粉末的组成与溶液组成相同，平均粒径在5-100 nm范围内，速度超过250g/h。然后在超高真空中用阴极发光检测这些材料的发射性能。一个重要的目标是探索在高度衰减的介质中导致光学增益的基本机制，从而使电磁辐射经历“反复”的散射事件并具有强烈的局域性。因此，在一个新兴的跨学科领域，为研究生和博士后提供了极好的培训。人们正在研究合适的跃迁和实验条件，以便高效、连续地在纳米荧光粉中产生紫外光和可见光受激发射，利用相干光学技术来探测它们的散射特性。通过产生无斑点、非相干光，紫外激光荧光粉有望与其他受激发光源完全不同。%这个项目研究在非常小的氧化物单晶的强散射粉末中遇到的全新的量子光学过程。从纳米粉末中产生连续的、紫外线和可见光的激光发射的电力有望导致在适应光源、显示器、光刻和改进的荧光粉中的许多应用。这种跨学科的研究为研究生和博士后研究助理提供了一个具有挑战性的培训场地，他们所在的新兴技术领域结合了最先进的化学、电子光谱学和相干光学测量。

9975542RandThis project investigates fundamentally new, quantum optical properties of strongly scattering powders of oxide nanocrystals doped with rare earth ions. Mirrorless laser emission is produced by excitation with electrons in the energy range 1-10 keV in the strong, multiple-scattering regime. Powders of alumina nanocrystals containing ultraviolet-emitting ions are synthesized by spraying alkoxide precursors through a flame, in a process that results in excellent particle uniformity, controllable size, and high purity. The use of soluble metallorganic precursors yields unagglomerated powders with compositions identical to the solution compositions and average particle diameters in the 5-100 nm range, at rates of over 250 g/h. The emissive properties of these materials are then examined by cathodoluminescence in ultrahigh vacuum. An important objective is to explore the fundamental mechanisms responsible for optical gain in media so highly attenuating that electromagnetic radiation undergoes "recurrent" scattering events and is strongly localized. Excellent training of graduate and postdoctoral students in an emerging cross-disciplinary field is thereby provided. Suitable transitions and experimental conditions are being studied for efficient, continuous generation of ultraviolet and visible stimulated emission in nanophosphors, utilizing coherent optical techniques to probe their scattering properties. Ultraviolet laser phosphors are expected to be quite unlike other stimulated emission sources by generating speckle-free, incoherent light.%%%This project investigates fundamentally new, quantum optical processes encountered in strongly scattering powders of very small, oxide single crystals. Electrical generation of continuous, ultraviolet and visible laser emission from nanopowders is expected to lead to numerous applications in conformable light sources, displays, lithography and improved phosphors. This inter-disciplinary research provides a challenging training ground for graduate students and postdoctoral research associates in an emerging technology area combining state-of-the-art chemistry, electron spectroscopy, and coherent optical measurements.***