Spectroscopic Study of New, Effective Up-Conversion Charging Process in Persistent Phosphors

持久性荧光粉中新型有效上转换充电过程的光谱研究

• 批准号: 1705707
• 负责人: Peter Kner
• 金额: $ 38.77万
• 依托单位: University of Georgia Research Foundation Inc
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2021-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1705707&HistoricalAwards=false
• 关键词: Spectroscopic; Study; New; Effective; Up

Non-technical Description: Afterglow (i.e. persistent luminescence) is a self-sustained luminescence phenomenon whereby a material (i.e. persistent phosphor) glows in the dark for hours after the excitation light source has been switched off. Nowadays persistent phosphors emitting in the visible and near-infrared spectral ranges are being used in daily life, e.g., security signs, emergency route signs, traffic signage, dials and displays, and medical research. However, the widespread use of persistent phosphors is greatly hindered because of the need of high-energy excitation light, mostly ultraviolet light, to charge the materials. Therefore, solutions to achieving effective excitation with low-energy light, particularly the visible light, are in demand. This project investigates a new charging process that enables low-energy visible-light sources (e.g. laser diodes) to be as effective as the commonly used high-energy ultraviolet light sources (e.g. ultraviolet lamps) in charging persistent phosphors. The outcomes of this research have a potential to open new strategies for studying and utilizing persistent phosphors. The project provides an interdisciplinary training experience to graduate, undergraduate and K-12 students in luminescent materials research and applications. The undergraduate and K-12 education is implemented through the existing programs at University of Georgia, such as the NSF-sponsored Peach State-Louis Stokes Alliance for Minority Participation program, NSF-sponsored Research Experiences for Undergraduates sites, and Young Dawgs program (for K-12 education).Technical Description: It is a general knowledge in persistent luminescence that high-energy ultraviolet light is usually necessary in order to effectively charge a persistent phosphor. However, the need of high-energy excitation compromises some applications where the ultraviolet light is unavailable or unsuitable. This project aims to tackle this limitation by investigating a new, two-photon up-conversion charging (UCC) process where low-energy visible-light sources (e.g. laser diodes) are as effective as the commonly used high-energy ultraviolet light sources (e.g. ultraviolet lamps) in charging persistent phosphors. In the UCC concept, two visible photons from a visible-light laser diode are successively absorbed by a UCC enabling ion (e.g. trivalent chromium ion) so that the high-energy delocalization state of the ion is reached and the electron traps in the phosphor are filled. The UCC enabling ions include trivalent chromium, divalent manganese, quadrivalent manganese, trivalent praseodymium, and trivalent neodymium. Several power-tunable visible-light laser diodes with wavelengths in the range of 400-700 nm are used as the excitation sources. New optical measurement techniques for UCC, such as UCC excitation spectroscopy, are under development in order to acquire spectral data that are essential for understanding the energy absorption, electron transfer, electron trapping and de-trapping processes involved in the UCC.

非技术描述：余辉（即持续发光）是一种自我维持的发光现象，在该现象中，材料（即持续的磷光体）在激发光源关闭后数小时在黑暗中发光。如今，在日常生活中使用了可见和近红外光谱范围内发出的持续磷光器，例如安全标志，紧急路线标志，交通标志，表盘和显示器以及医学研究。但是，由于需要高能量激发光（主要是紫外线）来为材料充电，因此持续的磷光剂的广泛使用受到了极大的阻碍。因此，需要低能光，尤其是可见光的光线，以实现有效激发的解决方案。该项目调查了一个新的充电过程，该过程使低能可见光来源（例如，激光二极管）在充电持久磷剂中充电中常用的高能紫外线光源（例如紫外线）与常用的高能紫外线光源（例如紫外线）一样有效。这项研究的结果有可能开放研究和利用持续磷光剂的新策略。该项目为毕业，本科和K-12学生提供了发光材料研究和应用的跨学科培训经验。本科和K-12教育是通过佐治亚大学的现有课程实施的，例如NSF赞助的桃子州 - 州路易斯 - 史对少数民族参与计划，NSF赞助的本科生的研究经验，以及年轻的DAWGS计划以及年轻的DAWGS计划（K-12教育）。为了有效地充电持续的磷。但是，对高​​能激发的需求损害了某些应用，而紫外线不可用或不合适的应用。该项目旨在通过调查新的两光子上转换充电（UCC）过程来解决这一局限性，在该过程中，低能量可见光来源（例如激光二极管）与常用的高能紫外线光源（例如，紫外线灯（例如，紫外线灯）在充满吸引力的耐伴随效果上一样有效。在UCC概念中，来自可见光激光二极管的两个可见光子被UCC启用离子（例如三价铬离子）依次吸收，因此可以达到离子的高能量离域状态，并填充磷中的电子陷阱。 UCC启用离子包括三价铬，二价锰，四价锰，三价Praseodymium和Trialent Neododim。具有波长在400-700 nm范围内的波长的几个可启动的可见光激光二极管用作激发源。为了获取对了解UCC中涉及的能量吸收，电子传递，电子捕获和消除捕获过程，UCC的新的光学测量技术（例如UCC激发光谱）正在开发中。