Browsing by Author "Stösser, Reinhard"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- ItemEffects of phase Separation and devitrification processes in oxide glasses on ESR spectra(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1997) Nofz, Marianne; Stösser, Reinhard; Scholz, GudrunThe consequences of phase Separation and devitrification processes for the ESR patterns of Fe³⁺ ions and oxygen hole centres in giassy and glassy-crystalline Systems are discussed. Analysis of the Fe³⁺ spectra by Simulation (including 4th order terms) allows their model-based Interpretation for homogeneous, phase-separated and devitrified samples as well. It is even possible to estimate the ratio of Fe³⁺ ions incorporated into the giassy matrix to those localized in the crystalline phase. An influence of irreversible structural reorganization in glasses on γ-irradiation-induced oxygen hole centres is detectable by studying their Saturation behaviour For the example of a barium Silicate glass studied here, pronounced passage effects could be detected at 77 K. In contrast, a devitrified sample of the same composition after γ Irradiation yielded the same spectral pattern at low microwave power, but only Saturation broadening was to be observed when rising the microwave power. In an annealed sample of anorthite composition (in mol%: 25CaO, 25AI₂O₃, 50SiO₂) progressive crystal growth was detectable using Fe³⁺ ions as probes.
- ItemOn the interaction of glasses with high-energy radiation - Combined ESR and optical studies(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1999) Nofz, Marianne; Reich, Christian; Stösser, Reinhard; Bartoll, Jens; Janata, EberhardThis paper will discuss some aspects of the induced physical processes and chemical reactions which are observed when Silicate and aluminosilicate glasses are exposed to UV radiation (248 nm; excimer laser), γ radiation (⁶⁰Co) and pulses of fast electrons (3.8 MeV). The stimulated emission and absorption of short-lived defects and Čerenkov radiation are detected in the optical ränge between 200 and 800 nm and on the microsecond time scale. Stahle hole centres (Si-0⁻/h⁺, Si-O-Al/h⁺) and electron centres (among others Zn⁺, Cd⁺, (Fe³⁺)⁻) are detected by ESR spectroscopy at room temperature. They show surprising differences in regard to their thermal stability, i.e., the distribution and mean value of their trap depths. Induced absorption in the UV/VIS range exhibits broad and overlapping bands, some of which can be partially assigned to centres detected by ESR spectroscopy. Therefore, UV/VIS spectroscopy provides complementary information, an induced absorption at 300 nm for example, which has no analogy in ESR measurements.