SGER: Quantum Electronic Properties of Ultraviolet Laser Phosphors

9975542rand本项目从根本上研究了掺杂稀土离子的强散射氧化物纳米晶体粉末的全新量子光学特性。无反光镜激光发射是由能量范围在1-10 keV的电子在强、多重散射区激发产生的。采用火焰喷射法制备了含紫外发射离子的氧化铝纳米晶体粉末，该方法具有颗粒均匀性好、尺寸可控、纯度高的特点。可溶金属有机前驱体的使用产生了与溶液组成相同的未团聚粉末，平均粒径在5-100纳米范围内，速率超过250克/小时。然后用超高真空阴极发光技术检测了这些材料的发射特性。一个重要的目标是探索负责介质中光学增益的基本机制，因此高度衰减的电磁辐射经历“反复”散射事件并被强烈定位。因此，在新兴的跨学科领域为研究生和博士后提供了优秀的培训。利用相干光学技术探测纳米荧光粉的散射特性，研究有效、连续产生紫外和可见光受激辐射的合适跃迁和实验条件。通过产生无斑点的非相干光，紫外激光荧光粉有望与其他受激发射源不同。这个项目从根本上研究了在非常小的氧化物单晶的强散射粉末中遇到的新的量子光学过程。从纳米粉末中产生连续的紫外和可见光激光，有望在光源、显示器、光刻和改进的荧光粉等领域得到广泛应用。这项跨学科的研究为研究生和博士后研究人员提供了一个具有挑战性的训练场地，在一个新兴的技术领域结合了最先进的化学、电子能谱和相干光学测量

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.***