Control of the anisotropy in the formatin of silver precipitates in Ag-Cl containing glass

在对玻璃析出物光致各向异性的研究过程中，发现光纤用掺锗硅玻璃对紫外激光照射具有高度的光敏性。特别是高压氢处理显著提高了光敏性。因此，通过测量锗掺杂二氧化硅在紫外区的光吸收、光致发光（PL）和电子自旋共振（ESR），重点研究了锗掺杂二氧化硅的光敏性。将安装在UVSOR b3a1线上的波动器发出的能量为36 eV的偏振光照射到掺锗硅玻璃上。对样品进行了光致发光和ESR测量。为了监测光照引起的光化学反应，测量了3.1和4.2 eV下的PL波段。PL的衰减遵循拉伸的指数函数，表明反应发生在锗掺杂二氧化硅的缺氧态。光照后观察到的锗E中心的ESR对外加磁场没有角依赖性。发现顺磁中心的形成涉及KrF准分子激光双光子吸收产生的电子-空穴对的非辐射弛豫。通过测量相位掩模照射形成的光栅的布拉格反射，研究了KrF激光照射引起的折射率变化。折射率的变化与紫外吸收带的形成有关。研究还发现，高剂量γ辐照可在硅玻璃中产生硅簇，硅簇在可见光区表现出光致发光。

During the course of the present research on the optically-induced anisotropy in the precipitates of glass, germanium-doped silica glass for optical fibers was found to be highly photosensitive against UV laser irradiation. Especially, the photosensitivity was significantily enhanced by a high-pressure hydrogen treatment. Thus, emphasis has been placed on the photosensitivity of germanuium-doped silica by means of the measurements of optical absorption in UV regions, photoluminescence (PL) , and electron spin resonance (ESR) .Polarized light with an energy of 36 eV from an undulator installed at BL 3A1 line of UVSOR was illuminated onto the germanium-doped silica glass. Photoluminescence and ESR measurements were carried out on the sample. In order to monitor photochemical reactions induced by light illumination, PL bands at 3.1 and 4.2 eV were measured. The decay of the PL follows a stretched exponential function, suggesting that the reaction occurs at the site of oxygen-deficient states in the germanium doped silica. The ESR of the germanium E'centers observed after the light illumination exhibit no angular dependence against the applied magnetic field.It is found that the formation of paramagnetic centers involves nonradiative relaxation of electron-hole pairs created by two-photon absorption of a KrF excimer laser. Refractive index changes induced by KrF laser illumination were investigated by the measurements of a Bragg reflection from a grating formed by illumination through a phase mask. The refractive index change was correlated with the formation of UV absorption bands. It is also found that high-dose gamma irradiation can produce clusters of Si in silica glass, which exhibit photoluminescene in the visible regions.