Spectroscopy and Thermoluminescence of LuAlO3:Ce

The present status of the LuAlO3:Ce scintillator is reviewed. Scintillation mechanism of this material is based on capture by Ce3+ of holes and then electrons from their respective bands. Results of spectroscopic and thermoluminescence experiments are presented to support this model

Persistent luminescence excitation spectroscopy of BaAl2O4:Eu2+,Dy3+

BaAl2O4:Eu2+,Dy3+ is related, both by structure and luminescence, to one of the best persistent luminescent phosphors, SrAl2O4:Eu2+,Dy3+. At room temperature (RT), the green persistent emission of BaAl2O4:Eu2+,Dy3+ remains visible for hours after ceasing irradiation. Similar to SrAl2O4, BaAl2O4 with hexagonal P6(3) structure, has two M2+ sites, but, limited optical activity from the 2nd site is observed in the emission of BaAl2O4:Eu2+,Dy3+-even at 77 K. Using combined approach of photoluminescence, thermoluminescence (TL), and persistent (excitation) luminescence measurements, the origin and properties of persistent luminescence of BaAl2O4:Eu2+, Dy3+ were studied in detail. Ultraviolet (UV) excited and persistent emission are identical and no contribution from the Eu2+ in the high-symmetry Ba site was observed. TL excitation spectra clarified the unstructured conventional excitation spectrum; now it is evident that defects or the Dy3+ co-dopant do not contribute to persistent luminescence via direct energy absorption. Mechanisms for persistent luminescence should thus be revised

Analysis of the quartz OSL decay curve by differentiation

A mathematical transformation based on differentiation is introduced that converts a Continuous Wave Optically Stimulated Luminescence (CW-OSL) decay curve composed of a number of exponentials into a spectrum like curve with different peaks. Peak areas of the transformed curve are equal to the time integrated OSL of the exponentials. It is shown that the peaks of the transformed curve are more separated then the original decay curve components. The transformation is applied to computer generated OSL curves and to measured CW-OSL decay curves of three different quartz samples. Advantages and limitations of this differentiation analysis method are discussed.</p

How to visualize quartz OSL signal components

The optically stimulated luminescence (OSL) signal of natural quartz measured under constant stimulation power (CW-OSL) is a featureless decay curve where underlying components cannot be identified easily. Visual interpretation of quartz OSL signals is easier if signals are shown in spectrum-like form. This can be achieved either through ramped stimulation, or by transforming a measured CW-OSL curve into a pseudo OSL curve. We show that both give similar results, but that transformation should be preferred as CW-OSL provides best signal-to-noise ratios. We present different transformation methods to obtain pseudo OSL curves and discuss the advantages and disadvantages of each method. In addition, we show that different pseudo OSL transformations can be used to emphasize specific aspects of the OSL signal. We conclude that transformation of CW-OSL to pseudo hyperbolically modulated OSL provides the most useful visualization of the quartz fast OSL component. Pseudo parabolic modulated OSL is the transformation of choice for showing the slow component(s). The pseudo OSL curves can be used for rapid visual inspection of the relative contribution of the OSL components prior to further analysis

Lanthanide energy levels in YPO4

International audienc

Thermal ionization and thermally activated crossover quenching processes for 5d-4f luminescence in Y3 A l5-x G ax O12: P r3+

© 2017 American Physical Society.We investigated thermally activated ionization and thermally activated crossover as the two possibilities of quenching of 5d luminescence in Pr3+-doped Y3Al5-xGaxO12. Varying the Ga content x gives the control over the relative energy level location of the 5d and 4f2:PJ3 states of Pr3+ and the host conduction band (CB). Temperature-dependent luminescence lifetime measurements show that the 5d luminescence quenching temperature T50% increases up to x=2 and decreases with further increasing Ga content. This peculiar behavior is explained by a unique transition between the two quenching mechanisms which have an opposite dependence of thermal quenching on Ga content. For low Ga content, thermally activated crossover from the 4f5d state to the 4f2(PJ3) states is the operative quenching mechanism. With increasing Ga content, the activation energy for thermally activated crossover becomes larger, as derived from the configuration coordinate diagram, while from the vacuum referred binding energy diagram the activation energy of thermal ionization becomes smaller. Based on these results, we demonstrated that the thermal quenching of Pr3+:5d1-4f luminescence in Y3Al5-xGaxO12 with x=0,1,2 is a thermally activated crossover while for x=3,4,5 it results from the thermal ionization

A test case for anomalous fading correction in IRSL dating

Infrared-stimulated luminescence (IRSL) dating of feldspars has the potential to date deposits beyond the age range of quartz optical (OSL) dating. Successful application of feldspar IRSL dating is, however, often precluded due to anomalous-fading, the tunnelling of electrons from one defect site to another. In this paper we test procedures proposed for anomalous-fading correction by comparing feldspar IRSL and quartz OSL dating results on a suite of samples from continental deposits from the southeastern Netherlands. We find that even after anomalous-fading correction IRSL ages underestimate the burial age of the deposits and argue that this may be a consequence of a dependency of anomalous fading rate on the dose rate and on the absorbed dose