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Yazar: Polymeris, George S. × Bölüm: Işık University, Faculty of Arts and Sciences, Department of Physics ×

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    Thermal quenching of thermoluminescence in quartz samples of various origins
    (Univ Agean, Dept Mediterranean Stud, 2010) Subedi, Bhagawan; Afouxenidis, Dimitrios; Polymeris, George S.; Bakoglidis, Konstantinos D.; Raptis, Spyridoula; Tsirliganis, Nestor C.; Kitis, George
    The effect of thermal quenching plays an important role in the thermoluminescence (TL) of quartz on which many applications of TL are based. In present work it is investigated that the thermal quenching parameters i.e. the activation energy W and the dimensionless parameter C, are more or less the same for every kind of quartzes or sample dependent on strong external treatment like a high temperature annealing. This preliminary investigation of seven quartz samples of different origin showed that the thermal quenching parameters W and C are common (universal) for most of the quartz samples.
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    Preliminary TL and OSL investigations of obsidian samples
    (Univ Agean, Dept Mediterranean Stud, 2010) Polymeris, George S.; Gogou, D.; Afouxenidis, Dimitrios; Rapti, Sofia; Tsirliganis, Nestor C.; Kitis, George
    Obsidian is a volcaniclastic mineral extremely hard to break, which was used in prehistoric Greece (and elsewhere in the World), in order to provide tools, weapons, knives and arrowheads. The present work aims to characterize this extremely precious tool stone by using both thermoluminescence (TL) and optically stimulated luminescence (OSL) techniques and investigate its potential use for luminescence dating purposes. Basic TL and OSL properties, such as TL and OSL thermal and optical stability, repeatability, TL and LM-OSL glow curve shape and mainly the linearity of the TL and OSL signals as a function of beta dose were investigated. Artificially irradiated samples indicate all promising luminescence features, such as the 110 degrees C TL peak and dose response sub-linearity for intermediate doses, quick and effective bleaching all over the entire TL glow curve, along with quite linear CW-OSL dose response for doses larger than 5 Gy. The lack of predose sensitisation indicates the suitability of the material for single aliquot measurements. Furthermore, several features provide indications that the signal does not relate to quartz, but in fact to other silicates. Unfortunately, both lack of bleaching ability for NIL signal, along with a peculiar shape of NOSL, provide major difficulties in dating applications.
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    Dating fossil root cast (Black Sea coast, Turkey) using thermoluminescence: Implications for windblown drift of shelf carbonates during MIS 2
    (Elsevier Ltd., 2016-05-16) Polymeris, George S.; Kitis, George; Güneç Kıyak, Nafiye; Theodosoglou, Eleni; Tsirliganis, Nestor C.; Ertek, Topçu Ahmet; Erginal, Ahmet Evren
    Rhizoliths are mostly sub-aerially exposed root prints which appear through removal of the rock units that cap them. A horizontal-lying residual of a rhizolith, consisting purely of soft inner core material of white color was recovered 10 km west of Şile, Istanbul, in northwest Turkey within laminated oolithic massive aeolianite. The inner part, consisting purely of calcium carbonate, was dated by applying thermoluminescence, while for the outer shelves optically stimulated luminescence of quartz was used for age assessment. The age of the CaCO3 infill occupying the original place of the decayed plant roots was found to be 26.8 (±5.0) ka, corresponding to MIS 2. When compared with the ages of the middle (105.2 ± 15.6 ka) and outer (127 ± 9 ka) layers, corresponding to the later stage of MIS 5e or early stage of MIS 5d, the inner core coincides with the last glacial period when the sea-level was lower than the present, promoting transportation of ooids by offshore winds in conjunction with the exposed shelf carbonates. Based on the results yielded, rhizolith is much younger than the host rock aeolianite and witnesses to last glacial sea level lowstand when removal of shelf carbonates by offshore winds was promoted from the exposed shallow shelf plain. The results provide strong evidence that rhizoliths may not be coeval with the aeolianites within which they are embedded.
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    TL and OSL response of turquoise for dosimetric application
    (University of Aegean, 2010) Subedi, Bhagawan; Afouxenidis, Dimitrios; Polymeris, George S.; Tsirliganis, Nestor C.; Paraskevopoulos, Konstantinos M.; Kitis, George
    Turquoise is one of the amongst first gem stones used in jewelry and possessing cultural value since 2000 BC (at least). This work attempts characterize this stone scientifically using both thermally (TL) and optically stimulated luminescence (OSL) techniques. The experimental investigation included 1) the study of the natural TL and OSL signals, 2) the reproducibility of TL sensitivity over repeated irradiation and TL readout cycles, 3) dependence of sensitivity on annealing temperatures and 4) the TL and OSL dose response curves. The potential use of the TL and OSL techniques in determination of provenance, accidental dosimetry and probably to authenticity and dating purposes are then discussed.
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    Investigating the thermally transferred optically stimulated luminescence source trap in fired geological quartz
    (Pergamon-Elsevier Science Ltd, 2014-03) Koul, Dileep K.; Patil, Pravinkumar G.; Oniya, Ebenezer O.; Polymeris, George S.
    The pre-dosed thermoluminescence (TL) emission of quartz has been found to be useful in retrospective dosimetry and archaeometry. Though the pre-dosed optically stimulated luminescence (OSL) and emissions have been reported to be similar, the former has been found to be un-reliable for the equivalent dose estimation. As this measurement protocol involves thermal heating at around 400 degrees C, the work reported in this paper investigated the influence of this heating on the OSL using fired specimens from various regions. The results suggested that the discrepancy in the behaviour of two emissions is caused by the presence of the thermally transferred optically stimulated luminescence (TT-OSL) induced by thermal-activation involved in the pre-dose treatment. This transferred signal was observed to be very significant in the case of samples containing a prominent higher-temperature TL peak at similar to 375 degrees C. The characterization of this signal based on (i) the nature of the glow curves, (ii) thermal-annealing of the OSL trap, (iii) observation of the TT-OSL, (iv) bleaching of the source trap and (v) the correlation between TL and OSL seems to suggest that the trap corresponding to this TL peak is the source trap in the TT-OSL emission mechanism.
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    The correlation of fast OSL component with the TL peak at 325 degrees C in quartz of various origins
    (Elsevier Science BV, 2010-02) Kitis, George; Güneç Kıyak, Nafiye; Polymeris, George S.; Tsirliganis, Nestor C.
    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 degrees 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 50s 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 200-400 degrees 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 200-400 degrees 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.
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    Component resolved OSL dose response and sensitization of various sedimentary quartz samples
    (Elsevier Ltd, 2007-02) Güneç Kıyak, Nafiye; Polymeris, George S.; Kitis, George
    The structure of the linearly modulated optically stimulated luminescence (LM-OSL) signal was studied for four sedimentary quartz samples, collected from different sites around Istanbul, Turkey. Applying a computerized deconvolution analysis to the LM-OSL curves, at least six individual components of first-order kinetics were identified and photoionization cross-section of each component was evaluated. The OSL dose-response curve of each component for each quartz sample was obtained, showing a remarkable differentiation from component to component. The behavior of a highly dosed sample to successive LM-OSL measurements was also studied showing a stable recuperation signal in the position of the "slow" and "medium" components and high resistance to OSL bleaching of the "slow" component. The individual sensitivity of each component as a function of the activation temperature was obtained. The sensitivity of each component was normalized over the respective sensitivity of the glow-peak at 110 degrees C of quartz in order to investigate the ability of the 110 degrees C glow-peak to act as a correction factor for all components of the LM-OSL curves examined.
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    A comparative morphological, compositional and tl study of tenedos (Bozcaada) and Sile aeolianites, Turkey
    (Univ Agean, 2012) Polymeris, George S.; Erginal, Ahmet Evren; Güneç Kıyak, Nafiye
    Aeolianites are carbonate-cemented deposits of coastal dune sands, mostly of Quaternary age. Even though aeolianite exposures on the coasts of the Mediterranean Sea are frequent, very few records have been documented from the coasts of either the Aegean or the Black Sea. The present study deals with evaluating and comparing both compositions and thermoluminescence (TL) ages of two recently reported samples of coastal aeolianites. Both were recovered at the Turkish coasts of Tenedos (Bozcaada) island, Aegean Sea and Şile, Western Black Sea. In the latter case, being the first record for the specific coastal area, the oldest age obtained was dated at 158±25 ka while the youngest age yielded was 108±14 ka. These values imply that both deposition and cementation occurred during the high sea stand of marine isotope stage 5 (MIS 5). In the case of Tenedos, the aeolianites were deposited between the early stage of the oxygen isotope stage 2 period (OIS 2) and the very late phase of the oxygen isotope stage 3 period (OIS 3). These latter TL results are in excellent agreement with a previous study of the same complex after applying OSL. Besides the ages, a number of luminescent features and properties in conjunction with compositional data suggest the dissimilarity for the quartz samples extracted from the aeolianites recovered at these two sampling sites, excluding thus any transport from one sampling site to the other, despite the short distance of the two sampling sites and the meteorological data regarding the preferable wind directions between them.
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    Investigating the thermally transferred optically stimulated luminescence source trap in fired geological quartz (vol 62, pg 60, 2014)
    (Pergamon-Elsevier Science Ltd, 2014-08) Koul, Dileep K.; Patil, Pravinkumar G.; Oniya, Ebenezer O.; Polymeris, George S.
    [No abstract available]
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    The firing temperature of pottery from ancient Mesopotamia, Turkey, using luminescence methods: a case study for different grain-size fractions
    (Wiley-Blackwell, 2014-10) Polymeris, George S.; Güneç Kıyak, Nafiye; Koul, Dileep K.; Kitis, George
    The assessment of the firing temperature of a prehistoric pottery sample collected from ancient Mesopotamia, Turkey was studied using luminescence techniques. The methods for this estimation involved the observation of the thermal and pre-dose sensitization with various re-firing temperatures for both TL and the OSL signals. In the former case, the 110 degrees C TL peak and the rest of the glow curve were used as proxies in this study. In the framework of a first attempt to investigate the impact of grain-size dependence on the sensitization of the luminescence signals, the aforementioned study was performed with four different pottery grain-size fractions: (i) less than 60m, (ii) 60-90m, (iii) 90-180m and (iv) 180-250m. The results clearly demonstrated the firing temperature mark of approximate to 500 degrees C in for the grain size of 90-180m, whileas in the case of the lower grain-size fractiona third proxy, the ratio of the pre-dosed to the thermal sensitization, was seen to indicate the firing temperature. The remaining two grain-size fractions failed to provide any meaningful results with regard to the firing temperature estimation. The dependence of the TL characteristics on the grain size was explained in the framework of the mixed mineralogy.