| Popis: |
Up to four broad thermoluminescence emission bands were observed in X-ray irradiated feldspars of different composition. Slow decrease of emission after X-ray irradiation indicates the presence of shallow traps in most feldspars. The glow curves were also very broad; the method of Hoogenstraaten led to activation energies between 52 and 105 kJ/mol and small frequency factors around 10 5 s -1 . Simultaneous measurements of isothermal changes in optical absorption and thermoluminescence intensity indicated transition from first to second order decay in most cases in qualitative agreement with the kinetics of defect formation by X-ray irradiation. The glow curves could also be decomposed into two curves with a first order decay preceding the second order process. The activation energies determined by both methods are in fair agreement, differences may be due to distributions of trap depths. Activation energies and the maxima of emission, absorption and photoconductivity were used for construction of energy level schemes for these radiation defects. Common excited states above the conduction band edge are suggested for all defects. |
