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Excitation states and defect formation in high purity silica glass under gamma-ray or excimer-laser irradiation

伽马射线或准分子激光照射下高纯石英玻璃的激发态和缺陷形成

基本信息

批准号：
03452156
负责人：
OHKI Yoshimichi
金额：
$ 4.22万
依托单位：
Waseda University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-03452156/
关键词：
silica glass excimer laser two-photon absorption process point defects synchrotron radiation radiation defect formation エキシマレ-ザ

项目摘要

The purpose of this study is to clarify the structural and optical properties of point defects in a-SiO_2, and their formation mechanisms under ionizing radiations or laser photons. The emphasis is placed on (i) the characterization of preexisting diamagnetic defects and radiation-induced paramagnetic defects, and (ii) the establishment of the link between the diamagnetic defects and radiation-induced paramagnetic defects. The outline of the present study is as follows.1.Defects and optical absorption bands associated with excess oxygen are identified. Two forms of excess oxygen are identified: peroxy linkage and interstitial oxygen. An optical absorption band at 3.8 eV is associated with peroxy linkages.2.Characterization of new paramagnetic defects induced by 7.9-eV photons is performed. With the help of computer simulation analyses of the ESR spectra, the paramagnetic defects are identified to be ClO_x radicals (x=2,3).3.Time-resolved photoluminescence (PL) measurements are carried out on a series of silicas under 7.9-eV pulsed laser excitation. Correlations of several PL bands with point defects are studied.4.Paramagnetic defects induced by 6.4-eV excimer laser are studied on a series of silicas. Effects of the oxygen stoichiometry and hydroxyl content on the defect species and their concentrations are observed. It is shown that precursor transformation dominates in laser-induced defect formation.5.Photon-energy dependence of the creation of paramagnetic defects is investigated by means of ESR and uv-vuv optical absorption measurements, using 6.4-eV and 7.9-eV photons, and gamma rays as irradiation sources. Correlations between the preexisting diamagnetic defects and laser-induced paramagnetic defects are investigated.6.The effect of hydrogen on the photogeneration of E' centers is studied by means of ESR and uv-vuv absorption measurements. It is found that the creation of E' centers from neutral oxygen vacancies is enhanced in the presence of hydrogen.

本研究的目的是阐明a-SiO_2中点缺陷的结构和光学性质，以及它们在电离辐射或激光光子作用下的形成机制。重点放在(I)先前存在的抗磁缺陷和辐射诱导的顺磁缺陷的表征，以及(Ii)在抗磁缺陷和辐射诱导的顺磁缺陷之间建立联系。本研究的概要如下：1.确定了与过量氧有关的缺陷和光学吸收带。确定了两种形式的过量氧：过氧键和间隙氧。在3.8 eV处有一个光学吸收带与过氧键有关。2.表征了7.9 eV光子引起的新的顺磁缺陷。通过对ESR谱的计算机模拟分析，确定了顺磁缺陷为ClO_x(x=2，3)。3.在7.9 eV脉冲激光激励下，对一系列二氧化硅样品进行了时间分辨光致发光(PL)测量。研究了几个发光带与点缺陷的关系。4.研究了6.4 eV准分子激光在一系列二氧化硅上诱导的顺磁缺陷。观察了氧化学计量比和羟基含量对缺陷种类及其浓度的影响。用6.4 eV和7.9 eV的光子和伽马射线作为辐照光源，通过ESR和UV-VUV光吸收测量，研究了顺磁缺陷形成的光能依赖性。研究了预先存在的抗磁缺陷和激光诱导顺磁缺陷之间的关系。6.通过ESR和UV-VUV吸收光谱研究了氢对E‘心光生的影响。结果表明，在氢的存在下，中性氧空位对E‘心的生成有促进作用。