Preliminary results towards the equivalence of transformed continuous-wave Optically Stimulated Luminescence (CW-OSL) and linearly-modulated (LM-OSL) signals in quartz (original) (raw)
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Analytical expressions for time-resolved optically stimulated luminescence experiments in quartz
Journal of Luminescence, 2011
Optically stimulated luminescence (OSL) signals can be obtained using a time-resolved optical stimulation (TR-OSL) method, also known as pulsed OSL. During TR-OSL measurements, the stimulation and emission of luminescence are experimentally separated in time using short light pulses. This paper presents analytical expressions for the TR-OSL intensity observed during and after such a pulse in quartz experiments. The analytical expressions are derived using a recently published kinetic model which describes thermal quenching phenomena in quartz samples. In addition, analytical expressions are derived for the concentration of electrons in the conduction band during and after the TR-OSL pulse, and for the maximum signals attained during optical stimulation of the samples. The relevance of the model for dosimetric applications is examined, by studying the dependence of the maximum TR-OSL signals on the degree of initial trap filling, and also on the probability of electron retrapping into the dosimetric trap. Analytical expressions are derived for two characteristic times of the TR-OSL mechanism; these times are the relaxation time for electrons in the conduction band, and the corresponding relaxation time for the radiative transition within the luminescence center. The former relaxation time is found to depend on several experimental parameters, while the latter relaxation time depends only on internal parameters characteristic of the recombination center. These differences between the two relaxation times can be explained by the presence of localized and delocalized transitions in the quartz sample. The analytical expressions in this paper are shown to be equivalent to previous analytical expressions derived using a different mathematical approach. A description of thermal quenching processes in quartz based on AlO 4 À /AlO 4 defects is presented, which illustrates the connection between the different descriptions of the luminescence process found in the literature.
Optically stimulated luminescence in synthetic quartz
Journal of Luminescence, 1994
Optically stiniulated luminescence (OSL). has been studied in synthetic quartz crystals. which had previously been exposed to Jtor X-irradiations. The main emission hands appeared at 380 and -~440 nm. The excitation spectra of these emission bands were now measured and showed both a maximum at 330nm. This maximum coincides with an excitation maximum of the phototransferred thermoluminescence (PTTL), indicating that the OSL and PTTL are due to the same traps. The emission intensities were found to depend linearly on the intensity of the stimulating 330 nm light, as well as on the dose of the /1-or X-irradiation over a wide range of doses. The results support the possibility of applying OSL in quartz for dosimetry and dating.
Radiation Measurements, 2008
The thermally activated characteristics (TAC) of the linearly modulated optically stimulated luminescence (LM-OSL) signals of seven quartz samples from different origin were studied relative to the TAC of their respective thermoluminescence (TL) glow-peaks at 110 • C. Within the framework of the study the TAC behavior of the LM-OSL was investigated by measuring the OSL signal at room temperature (RT) with the 110 • C glow-peak present during OSL measurements, as well as, at 125 • C without the glow-peak at 110 • C removed by a cut-heat at 180 • C prior to OSL measurement. The LM-OSL curves were analyzed into individual components using a computerized deconvolution procedure. It was found that all individual LM-OSL components of each kind of quartz follow the TAC behavior of the respective TL glow-peak at 110 • C. The fourth component of the LM-OSL curve, centered at about t m = 400 s, appeared when the OSL measurements were performed at RT, whereas it was absent when the OSL measurement were performed at 180 • C. It is suggested that this component is closely related with the TL glow-peak at 110 • C.
Geochronometria, 2021
The post-infrared (post-IR) pulsed blue light stimulated luminescence (PBLSL) signal has been employed to determine the equivalent dose (De) of feldspar contaminated quartz grains, but it sometimes suffers from the interference of feldspars. Since the green light stimulated luminescence (GLSL) signal of feldspars might be more reduced by a prior IR stimulation, we compared the characteristics of post-IR PBLSL and post-IR pulsed GLSL (post-IR PGLSL) signals of quartz and feldspars in this study to evaluate the feasibility of employing the green light for pulsed stimulation. We investigated the effect of the signal integration period, pulsed stimulation temperature, and prior IR stimulation temperature on the intensities of post-IR PBLSL and post-IR PGLSL of quartz and feldspars, and evaluated the potential feldspar interference on these two signals for the hypothetical and artificial quartz-feldspar mixture. The results demonstrate a lower feldspars contribution for the post-IR PGLSL...
On the separation of quartz OSL signal components using different stimulation modes
2008
We investigate both theoretically and experimentally the effect of stimulation mode on the separation of quartz optically stimulated luminescence (OSL) components. We find that, when assuming first-order kinetics with the detrapping probability proportional to stimulation intensity, the OSL signal is a function of the cumulative stimulation energy and not affected by the stimulation mode. This is confirmed by close correspondence between continuous wave (CW), linearly modulated (LM) and hyperbolically modulated (HM) OSL data for some of the samples studied. For other samples the data obtained using LM stimulation differ from that obtained using the other stimulation modes. This may be due to a contribution to the OSL signal from feldspars, or it may indicate that the behaviour of these samples is not adequately described by first-order kinetics. We suggest that CW stimulation is the method of choice for dating purposes as it allows the fastest readout with the greatest signal-to-noise ratio, and because it has a constant background. HM stimulation provides a good alternative when higher resolution is needed for the initial part of the shine-down curve.
Characteristics of time-resolved luminescence in quartz
Radiation Measurements, 2000
Time-resolved luminescence measurements were performed with samples of synthetic quartz (Sawyer Premium Q) and granular quartz extracted from ceramics and sediment samples under pulsed (H5 ns) laser stimulation (OPO). The luminescence was detected in the UV region using colour glass ®lters (FWHM 280±380 nm). The time-resolved spectrum is dominated by a single exponential decay that remains substantially unaltered when the stimulation wavelength is changed from 600 to 450 nm indicating that the same recombination process is being observed. The lifetime measured at room temperature was 4020X6 ms for the synthetic quartz; at elevated temperatures the measured lifetime is reduced in a manner that is consistent with a competitive non-radiative recombination process (thermal quenching). An average lifetime of 3320X3 ms was obtained for seven samples of granular quartz, indicating a common recombination process in these natural samples that diers from the value for synthetic quartz. 7
Radiation Measurements, 2003
Over the last few years, we have become increasingly conÿdent that quartz is a reliable natural dosimeter for sediment dating. Nevertheless, there is only a limited understanding of the behaviour of the di erent components of optically stimulated luminescence (OSL) from quartz. Recent single-aliquot dose-evaluation protocols seem to be relatively free of complications when applied to quartz dominated by the fast OSL component coming from 325 • C TL region, but this may not be true for quartz in which other components are more signiÿcant. An adequate understanding of how di erent OSL components behave during various measurement cycles is critical to ensuring that our dose evaluation protocols are robust and it is also important to our interpretation of the variation of apparent dose with optical stimulation time for identiÿcation of partial bleaching.
INVESTIGATION OF THE OSL SIGNAL FROM VERY DEEP TRAPS IN NATURAL QUARTZ
It has been recently reported by several studies that a thermally transferred optically stimulated luminescence (TT-OSL) signal from quartz grains can be used to extend the dating range for quartz samples. The TT-OSL signals are believed to consist of a recuperated OSL (ReOSL) component and a basic-transferred OSL (BT-OSL) component. In the present work the TT-OSL signals from several types of unfired quartz samples were studied. A special protocol was used, which allowed the measure the OSL from very deep traps (VDT) as a function of the OSL stimulation temperature. It was found that all quartz samples exhibit TT-OSL signals, which are depended on sample and on the OSL stimulation temperature. The activation energy of the process was evaluated and the influences of the TT-OSL on the ReOSL dating protocol are discussed.
The correlation of fast OSL component with the TL peak at in quartz of various origins
Journal of Luminescence, 2010
The fast component of the optically stimulated luminescence (OSL) signal in quartz is the basic tool for the optical dating. Its relation with the thermoluminescence (TL) glow-peak at about 325 3 C is well established for naturally irradiated quartz. This relationship is also an important part of a general model for quartz on which many theoretical simulations of various OSL experimental results have been based. In the present work this relationship is systematically investigated in nine quartz samples of different origin. The linearly modulated OSL (LM-OSL) curves of all quartz samples for stimulation time less than 50 s consists of two components discriminated easily by a computerized curve deconvolution (CCD) analysis. By comparing the un-bleached to the respective bleached TL glow-curve, it is found that the system of these two fast OSL components is directly related with only a small portion of the electron traps responsible for the TL glow-peaks in the temperature region 2002400 3 C. By increasing the stimulation times, besides the two fast components, the medium and the slow components are also obtained. The medium and slow components are clearly related with the main body of the electron traps responsible for TL glow-peaks in the same temperature region 2002400 3 C. Despite their different origin all quartz samples show an appreciable homogeneity concerning the number and time position of the individual components, whereas, the relative TL/OSL intensities vary strongly from sample to sample with the integrated TL intensity being generally much less than the integrated OSL intensity.