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Mr. Zhou, a Ph.D. graduate student, and

Collaborative Research: Multi-Photon Phosphors Based on Vacuum Ultraviolet Excitation R. S. Meltzer , University of Georgia (DMR-0305400).

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Mr. Zhou, a Ph.D. graduate student, and

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  1. Collaborative Research: Multi-Photon Phosphors Based on Vacuum Ultraviolet Excitation R. S. Meltzer, University of Georgia (DMR-0305400) Efforts are underway to develop a new generation of mercury-free fluorescent lamps with improved efficiency. A near unity quantum yield has been demonstrated using photon cascade emission (PCE) of Gd3+ sensitized by VUV excitation of the self-trapped exciton (STE) in ScBO3. In PCE an ion decays in a sequential two-step decay thereby emitting two photons for each photon absorbed (quantum splitting). The figure shows the STE emission of pure ScPO4(red curve) at 210 nm. In Gd-doped ScPO4 (blue curve) the STE emission is almost absent in favor of emission from the 6G and 6P states of Gd3+. The 6G state emits sequentially a red (600 nm) and UV(313 nm) photon. The total quantum yield is 1 photon out for each input photon. While this still lies below the desired value of at least 1.5 it demonstrates a new route to efficiently populate the 6G state of Gd3+ for quantum cutting application either through PCE or, alternatively, a cross relaxation energy transfer scheme.

  2. Collaborative Research: Multi-Photon Phosphors Based on Vacuum Ultraviolet Excitation R. S. Meltzer, University of Georgia (DMR-0305400) Two Ph.D. students and two visiting scholars, Professor Hyo Jin Seo (Pukyong National University, Korea) and Dr. Sergey Feofilov, (Ioffe Institute in St. Petersburg, Russia), are currently involved with this project. This research provides an opportunity for the students to gain expertise in phosphor development and to acquire the fundamental concepts in the optical properties of solids, especially those of rare earth doped insulators which form the basis for many phosphors. The training includes the gamut of techniques involved in vacuum ultraviolet (VUV) spectroscopy. Close cooperation in this project with scientists at Osram Sylvania allow students to understand the interfacing of research and development in an industrial setting. Collaborating in this project is Professor Keszler’s group at Oregon State University; they design and produce the phosphors used in this effort. Students at the two Universities see first hand the synergy necessary to develop new materials. Mr. Zhou, a Ph.D. graduate student, and Dr. Feofilov, a visiting scientist, are shown operating the VUV spectroscopy system.

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