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（即持久发光）是一种自持续发光现象，其中材料（即持久磷光体）在激发光源关闭后在黑暗中发光数小时。目前，在可见光和近红外光谱范围内发射的持久性磷光体正用于日常生活中，例如，安全标志、紧急路线标志、交通标志、拨号盘和显示器以及医学研究。然而，持久性磷光体的广泛使用受到很大阻碍，因为需要高能量激发光，主要是紫外光，来给材料充电。因此，需要用低能量光（特别是可见光）实现有效激发的解决方案。本项目研究一种新的充电过程，使低能量可见光光源（如激光二极管）能够像常用的高能量紫外线光源（如紫外线灯）一样有效地为持久性荧光粉充电。这项研究的结果有可能为研究和利用持久性磷光体开辟新的策略。该项目为研究生，本科生和K-12学生提供发光材料研究和应用的跨学科培训经验。本科和K-12教育是通过格鲁吉亚大学现有的计划实施的，如NSF赞助的桃州路易斯斯托克斯少数民族参与计划联盟，NSF赞助的本科生研究经验网站和年轻的道格计划（适用于K-12教育）。技术说明：在持久发光中，通常需要高能紫外光以有效地给持久磷光体充电是公知的。然而，高能量激发的需要损害了紫外光不可用或不适合的一些应用。该项目旨在通过研究一种新的双光子上转换充电（UCC）过程来解决这一限制，在该过程中，低能量可见光源（例如激光二极管）与常用的高能量紫外光源（例如紫外线灯）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使能离子（例如三价铬离子）连续吸收，使得达到离子的高能离域状态并且填充磷光体中的电子陷阱。UCC使能离子包括三价铬、二价锰、四价锰、三价镨和三价钕。几个功率可调谐的可见光激光二极管的波长在400-700 nm的范围内被用作激发源。新的光学测量技术的UCC，如UCC激发光谱，正在开发中，以获取光谱数据，是必不可少的了解能量吸收，电子转移，电子捕获和脱陷过程中所涉及的UCC。