5 research outputs found
The relation between optical bleaching and sedimentological features of fluvial deposits in the Toruń Basin (Poland)
Distributions of equivalent doses (DE) obtained by the Single Aliquot Regenerative-dose (SAR) OSL method applied for large aliquots of coarse quartz grains extracted from fluvial sediments are presented and analysed with respect to a fluvial palaeoenvironment. The Nowe Dąbie and Łochowo fluvial succession from the western part of Toruń Basin (eastern part of Noteć–Warta streamway, Toruń-Eberswalde ice-marginal valley) was analysed. The fluvial depositional conditions controlling the extent of daylight bleaching are reconstructed by sedimentological studies. The relation between the amount of bleaching and sedimentological properties of fluvial deposits indicate that ripple cross-laminated sands that accumulated on the floodplain and horizontally-bedded sands deposited in shallow channels are more appropriate for OSL dating than sands derived from the deep channel. Along with luminescence results obtained for the river deposits, data measured from an ancient pottery sample, ensuring complete reset of the OSL signal, are presented, compared to and discussed. On this base the poorly bleached sediment samples are identified and an adjustment factor is introduced for correcting their OSL dating results in order to avoid age inversion. The application of the adjustment factor is found to minimize overestimation of OSL ages of sediments
Charge Traps in Ce-Doped CaF and BaF
Thermoluminescence of CaF:Ce, BaF, and BaF:Ce irradiated at room temperature is reported. X-ray induced emission spectra of the samples show that both excitonic (due to e+V recombination) and Ce d-f luminescence may contribute to thermoluminescence signal. The simple Randall-Wilkins model is used to deconvolute glow curves into seven to eight first-order peaks. Parameters of all traps are calculated and correlations between peaks in the curves of the examined materials are discussed
Luminescence from β-Irradiated Graphene Layers
We found that β-irradiated samples of crystallite graphite and multi-walled carbon nanotubes emit light during heating above room temperature. This behaviour is rather surprising for semimetals. Due to the lack of deep enough energy gap, this optical emission cannot be associated with interband transitions, as it is usually assumed in a thermally stimulated luminescence model. We suppose that the reported accumulated luminescence is the result of thermally stimulated relaxation of some kind of defects created in graphene structures by ionising radiation and therefore we offer to name it the relaxoluminescence. We anticipate the relaxoluminescence to be a starting point for developing a new spectroscopic method for nanotechnology. It can also throw a new light on the nature of defects, which are suspected of being responsible for strange magnetic effects in carbon
Quartz luminescence applied in palaeoenvironmental reconstruction of a dune
Optically stimulated luminescence (OSL) and thermoluminescence (TL) dating
were applied for studying the evolution of a dune at the archaeological site of
Kałdus (Lower Vistula Valley, Poland), where excavation revealed a settlement
sequence. The dating results are supported by investigations of optical bleaching
characteristics of the dune quartz. The luminescence studies presented here are
a part of a wider interdisciplinary project studying the dynamics of the local
geomorphology and its relationship to human activity at the site from prehistoric
times until early medieval ages