Time-resolved luminescence from quartz : An overview of contemporary developments and applications
Chithambo, M.L. ; Ankjærgaard, C. ; Pagonis, V. - \ 2016
Physica B: Condensed Matter 481 (2016). - ISSN 0921-4526 - p. 8 - 18.
Feldspar - Luminescence lifetimes - Quartz - Time-resolved optical stimulation
Time-resolved optical stimulation of luminescence has become established as a key method for measurement of optically stimulated luminescence from quartz, feldspar and α-Al2O3:C, all materials of interest in dosimetry. The aim of time-resolved optical stimulation is to separate in time the stimulation and emission of luminescence. The luminescence is stimulated from a sample using a brief light pulse and the emission monitored during stimulation in the presence of scattered stimulating light or after pulsing, over photomultiplier noise only. Although the use of the method in retrospective dosimetry has been somewhat limited, the technique has been successfully applied to study mechanisms in the processes leading up to luminescence emission. The main means for this has been the temperature dependence of the luminescence intensity as well as the luminescence lifetimes determined from time-resolved luminescence spectra. In this paper we review some key developments in theory and applications to quartz including methods of evaluating lifetimes, techniques of evaluating kinetic parameters using both the dependence of luminescence intensity and lifetime on measurement temperature, and of lifetimes on annealing temperature. We then provide an overview of some notable applications such as separation of quartz signals from a quartz-feldspar admixture and the utility of the dynamic throughput, a measure of luminescence measured as a function of the pulse width. The paper concludes with some suggestions of areas where further exploration would advance understanding of dynamics of luminescence in quartz and help address some outstanding problems in its application.
Validating post IR-IRSL dating on K-feldspars through comparison with quartz OSL ages
Kars, R.H. ; Busschers, F.S. ; Wallinga, J. - \ 2012
Quaternary Geochronology 12 (2012). - ISSN 1871-1014 - p. 74 - 86.
Feldspar - Luminescence dating - OSL - Post IR-IRSL - Quaternary - Sediments
Recent developments have opened up the possibilities of using potassium feldspar for dating Pleistocene sediments; a stable (less-fading) part of the infrared stimulated luminescence (IRSL) signal can be selected by largely depleting the unstable part of the IR signal, using a combination of thermal and IR stimulation: post IR-IRSL dating (pIR-IRSL).This study aims to test the validity of pIR-IRSL dating on feldspars. We obtained pIR-IRSL ages on a large suite of samples from several locations in the Netherlands area, covering a wide range of depositional environments and ages. Age control was provided by quartz optically stimulated luminescence (OSL) ages on the same samples; these ages were shown to accord with geological age constraints. Comparison with IRSL ages enabled us to evaluate the improvement that pIR-IRSL dating provides over conventional IRSL methods.The majority of feldspar ages obtained with pIR-IRSL showed good agreement with both the quartz OSL ages and the geological age constraints. Our study demonstrates that pIR-IRSL dating is more robust than conventional IRSL and should be the method of choice in feldspar luminescence dating of Pleistocene sediments.
A test case for anomalous fading correction in IRSL dating
Wallinga, Jakob ; Bos, Adrie J.J. ; Dorenbos, Pieter ; Murray, Andrew S. ; Schokker, Jeroen - \ 2007
Quaternary Geochronology 2 (2007)1-4. - ISSN 1871-1014 - p. 216 - 221.
Anomalous fading - Feldspar - IRSL - Luminesence dating - Quartz
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.
Luminescence dating of Netherland's sediments
Wallinga, J. ; Davids, F. ; Dijkmans, J.W.A. - \ 2007
Netherlands journal of geosciences 86 (2007)3. - ISSN 0016-7746 - p. 179 - 196.
Feldspar - Luminescence dating - OSL - Quartz - Quaternary
Over the last decades luminescence dating techniques have been developed that allow earth scientists to determine the time of deposition of sediments. In this contribution we revity: 1) the development of the methodology, 2) tests of the reliability of luminescence dating on Netherlands' sediments; and 3) geological applications of the method in the Netherlands. Our review shows that optically stimulated luminescence dating of quartz grains using the single aliquot regenerative dose method yields results in agreement with independent age control for deposits ranging in age from a few years up to 125 ka. Optical dating of quartz has successfully been applied to sediments from a wide range of depositional environments such as coastal dunes, cover sands, fluvial channel deposits, colluvial deposits and fimic soils. These results demonstrate that optical dating is a powerful tool to explore the natural archive of the Netherlands' subsurface.
Electrons in feldspar II : A consideration of the influence of conduction band-tail states on luminescence processes
Poolton, N.R.J. ; Ozanyan, K.B. ; Wallinga, J. ; Murray, A.S. ; Bøtter-Jensen, L. - \ 2002
Physics and Chemistry of Minerals 29 (2002)3. - ISSN 0342-1791 - p. 217 - 225.
Effective mass - Feldspar - Hopping transport - Luminescence - Mobility edge
Most natural feldspars contain many charged impurities, and display a range of bond angles, distributed about the ideal. These effects can lead to complications in the structure of the conduction band, giving rise to a tail of energy states (below the high-mobility conduction band) through which electrons can travel, but with reduced mobility: transport through these states is expected to be thermally activated. The purpose of this article is twofold. Firstly, we consider what kind of lattice perturbations could give rise to both localized and extended conduction band-tail states. Secondly, we consider what influence the band tails have on the luminescence properties of feldspar, where electrons travel through the sample prior to recombination. The work highlights the dominant role that 0.04-0.05-eV phonons play in both the luminescence excitation and emission processes of these materials. It also has relevance in the dating of feldspar sediments at elevated temperatures.
Electrons in feldspar I : On the wavefunction of electrons trapped at simple lattice defects
Poolton, N.R.J. ; Wallinga, J. ; Murray, A.S. ; Bulur, E. ; Bøtter-Jensen, L. - \ 2002
Physics and Chemistry of Minerals 29 (2002)3. - ISSN 0342-1791 - p. 210 - 216.
Defects - Effective mass - Feldspar - Luminescence - Wavefunction
The purpose of this article is to make an initial consideration of the physical properties of electrons trapped at classic hydrogenic lattice defects in feldspar. We are particularly interested to determine the radial extent of the electron wavefunctions in the ground and excited states. It is shown that for NaAlSi3O8, the ground-state wavefunction is expected to be confined well within a single lattice unit cell, but the first excited state is far more extensive, being spread over several unit cells. This aspects is of direct relevance to understanding the nature of various luminescence processes in the materials. Under low-energy optical stimulation (hv ∼ 1.4 eV), luminescence can be a competitive process between direct electron-hole tunnelling recombination (with the charge still trapped at the defect sites), and free-to-bound recombination (after the excited state electron accesses the conduction band). We show that analysis of the thermal behaviour of the luminescence can be used to separate the two processes.