Dichroism in the absorption spectrum of photobleached ion-implanted silica

The optical absorption spectrum of ion-implanted silica is shown to become dichroic when it is photobleached with polarized 248-nm light. The dichroism is modeled by a photobleaching process that bleaches color centers preferentially depending on their local orientation with respect to the polarization of the photobleaching light. A similar photobleaching process may occur in photosensitive fiber, thus providing a possible explanation for the birefringence that is observed in the photoinduced index change

Formation and bleaching of strong ultraviolet absorption bands in germanium implanted synthetic fused silica

Germanium ions have been implanted in fused silica using ion beams having energies of 3 and 5 MeV and doses ranging from 1×1012 to 5×1014 ions/cm2. For wavelengths shorter than 400 nm, the optical absorption increases strongly with two absorption bands appearing at 244 and 212 nm. The ion-induced optical absorption can be bleached almost completely by irradiation with 249 nm excimer laser light. Ion implantation also increases the refractive index of silica near the substrate surface. At 632.8 nm a refractive index increase of more than 10-2 has been measured. This decreases by 4×10-3 upon bleaching with 249 nm light

The design and calibration of a versatile PIXE/RBS facility

The design and performance of a PIXE (Proton Induced X-ray Emission) facility for trace element analysis is presented, with emphasis on those features which enhance the throughput and sensitivity. An on demand pulse pileup rejection system reduces the spectral distortion and increases the data collection rate. Special precautions are taken to minimize all sources of background and the calibration procedure is described

The design and calibration of a versatile PIXE/RBS facility

The design and performance of a PIXE (Proton Induced X-ray Emission) facility for trace element analysis is presented, with emphasis on those features which enhance the throughput and sensitivity. An on demand pulse pileup rejection system reduces the spectral distortion and increases the data collection rate. Special precautions are taken to minimize all sources of background and the calibration procedure is described.Le développement et les performances d'un montage PIXE (proton induced X-ray emission) sont décrits pour l'analyse quantitative des éléments traces. L'ensemble a été conçu en vue d'une sensibilité et d'une fiabilité accrues ainsi que pour l'analyse de routine d'un grand nombre d'échantillons à un coût minimal. Un système de pulsations électrostatiques du faisceau a été développé dans le but de diminuer le temps mort et les empilements inévitables avec les constantes de temps nécessaires à l'obtention d'une très haute résolutiou. Des précautions spéciales ont été prises pour minimiser toutes les sources de bruit de fond. La procédure de calibration du montage est aussi décrite