Collaborative Research: Multiphoton Phosphors Based on Vacuum Ultraviolet Excitation

这个实验研究计划是针对多光子荧光粉的发展。 这些材料将初始VUV高能光子转换为两个较低能量的可见光子，从而建立可以大于1的效率量子。 这里定义的方法是利用镧系离子之间的能量转移过程来实现多光子过程。 一个镧系离子吸收真空紫外光子。 随后是交叉弛豫能量转移过程，其中最初激发的离子与不同的离子共享其能量的一部分。 两个离子都留下足够的能量以各自发射可见光光子，从而有效地利用来自灯放电的VUV光子来产生两个可见光子。 三个方案将被检查的能量转移，涉及4fn和4fn-15 d配置的镧系离子。 从文献数据的能量水平的镧系元素和它们的依赖于主机材料，一些离子对和适当的主机已被选定的研究，将最大限度地提高成功的机会。 由于这些计划涉及使用的高激发态的固体位于附近的导带的边缘，局部和离域状态的混合可能会发生，光电离和电荷转移过程可能会使问题复杂化，这将是必要的，以解决一些基本问题的性质和动力学的这些高激发态从物理和材料的角度来看。 该项目将由三个小组合作进行。 格鲁吉亚大学的物理小组将对磷光体进行光学表征，并研究其高激发态的动力学特性。 俄勒冈州州立大学的化学小组将生产所需的磷光体并优化其性能，他们还将开发可能具有所需性能的新组合物。 欧司朗西尔瓦尼亚的科学家们将为该项目贡献他们的时间，为荧光粉的开发和评估提供实验和理论支持，特别是关于它们在真实的灯具设备中的实际用途。美国利用其近25%的电能预算来满足我们社会的照明需求。 目前的荧光灯的壁插效率约为30%，废弃后会导致大量汞排入环境。 拟议的研究将提供急需的深入了解的过程和材料，这是必要的飞跃，以一种新的多光子荧光粉技术和一种新的形式的高效照明，这将导致大幅减少能源消耗和消除汞在照明中。 该项目将涉及三个小组的合作：格鲁吉亚大学的物理学家，俄勒冈州州立大学的化学家和欧司朗西尔瓦尼亚的工业科学家。 学生将深入了解多光子过程和材料设计，为未来在照明行业或照明行业的贡献提供基础。

This program of experimental research is directed to the development of multiphoton phosphors. These materials convert an initial VUV high-energy photon into two visible photons of lower energy, thereby establishing a quantum of efficiency that can be greater than one. The approach defined here is to use energy-transfer processes among lanthanide ions to implement the multiphoton process. One lanthanide ion absorbs the VUV photon. This is followed by a cross-relaxation energy-transfer process in which the initially excited ion shares a portion of its energy with a different ion. Both ions are left with enough energy to each emit a visible photon of light, thereby efficiently utilizing the VUV photon from the lamp discharge to produce two visible photons. Three schemes will be examined for the energy transfer that involve both the 4fn and the 4fn-15d configurations of the lanthanide ions. From literature data on the energy levels of the lanthanides and their dependence on host material, a number of ion pairs and appropriate hosts have been selected for study that will maximize the chance for success. Since these schemes involve the use of highly excited states of solids located near the edge of the conduction band where mixing of localized and delocalized states can occur and where photoionization and charge-transfer processes can complicate the problem, it will be necessary to address some of the fundamental issues concerning the nature and dynamics of these highly excited states from the physics and materials perspectives. The project will be conducted by collaboration among three groups. The physics group at the University of Georgia will perform the optical characterization of the phosphors and study the dynamical properties of their highly excited states. The chemistry group at Oregon State University will produce the required phosphors and optimize their properties, and they will also develop new compositions that are likely to have the desired properties. Scientists at Osram Sylvania will contribute to the project with their time providing both experimental and theoretical support on the development and evaluation of phosphors, especially regarding their practical usefulness in real lamp devices.The U.S. utilizes almost 25% of its electricity-energy budget to satisfy the lighting requirements of our society. Current fluorescent lamps have a wall-plug efficiency of about 30% and their discard results in the dumping of large amounts of mercury into the environment. The proposed research will provide much needed insight into the processes and materials that are necessary to make the leap to a new multiphoton-phosphor technology and a new form of high-efficiency lighting that will lead to a substantial reduction of energy consumption and the elimination of mercury in lighting. The project will involve collaboration among three groups; physicists at the University of Georgia, chemists at Oregon State University, and industrial scientists at Osram Sylvania. Students will develop an in-depth understanding of multiphoton processes and materials design, providing a base for future contributions in the lighting industry or academe.