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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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    A new late holocene eolianite record from Altinkum Beach, North Cyprus
    (Scientific technical research council Turkey-Tubitak, 2012-06) Erginal, Ahmet Evren; Güneç Kıyak, Nafiye; Ertek, Topçu Ahmet
    In this study, we investigated the main depositional characteristics and obtained Optically Stimulated Luminescence (OSL) ages of coastal eolianite on the north coast of Cyprus, where this occurrence had not previously been recorded. Based on EDX/SEM and XRD data and field observations, the studied eolianite that crops out between elevations of 1 m and 14 m a.s.l. is made up predominantly of quartz grains, most of which consist of medium- to fine-grained sand. The rock comprises aragonite, calcite and quartz with lesser amounts of bornite and hematite as accessory minerals. OSL ages indicated that the initial deposition of eolianite sands took place at 1.51 +/- 0.21 ka years ago.
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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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    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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    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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    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.
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    Optical stimulated luminescence dating study of eolianite on the Island of Bozcaada, Turkey: Preliminary results
    (The Coastal Education and Research Foundation, 2010-07) Güneç Kıyak, Nafiye; Erginal, Ahmet Evren
    In the present paper, eolianite exposed on the south coast of the semiarid island of Bozcaada, Turkey, was investigated on the basis of geomorphologic and petrographic data, and optically stimulated luminescence (OSL) dating results. The eolianite is lithic arenite in composition and contains abundant quartz, calcite, and various lithoclasts amalgamated with micritic calcite, sparitic calcite, and meniscus cements. Within the youngest layers standing at 1-2 m above sea level, the rock contains rhizoliths with or without carbonaceous fills. The OSL ages obtained ranged between 24.21 +/- 1.53 ka and 16.18 +/- 1.70 ka, suggesting that eolianite constitutes an example of low stand deposits coinciding with oxygen isotope stage 2 (OIS-2).
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    New quartz technique for OSL dating of limestones
    (2010) Liritzis, Ioannis; Drivaliari, N.; Polymeris, George S.; Katagas, Christos G.
    The equivalent dose De determination of limestone-made ancient constructions by thermoluminescence (TL) prevents accurate measurements and requires plateau test of bleached curves. Optical stimulated luminescence (OSL) of quartz and feldspar minerals for surface dating is routinely applied for De but not for limestones. Here the OSL of present traces of such minerals removed with powder from surface limestone bleached by sunlight overcomes this issue and offers an alternative way for De. This is verified with further test examples.
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    Thermoluminescence as a probe in bioactivity studies; the case of 58S sol-gel bioactive glass
    (IOP Publishing Ltd, 2011-10-05) Polymeris, George S.; Goudouri, Ourania Menti; Kontonasaki, Eleana; Paraskevopoulos, Konstantinos M.; Tsirliganis, Nestor C.; Kitis, George
    The formation of a carbonated hydroxyapatite (HCAp) layer on the surface of bioactive materials is the main reaction that takes place upon their immersion in physiological fluids. To date, all techniques used for the identification of this HCAp formation are rather time consuming and not well suited to detailed and rapid monitoring of changes in the bioactivity response of the material. The aim of this work is to explore the possibility of using thermoluminescence (TL) for the discrimination between different bioactive responses in the case of the 58S bioactive glass. Results provided strong indications that the 110 degrees C TL peak of quartz can be used effectively in the study of the bioactive behaviour of 58S bioactive glass, since it is unambiguously present in all samples and does not require deconvolution analysis. Furthermore, the intensity of the 110 degrees C TL peak is proven to be very sensitive to the different bioactive responses, identifying the loss of silica which takes place at the first stages of the sequence. The discontinuities of the 110 degrees C TL peak intensity plot versus immersion time at 8 and 1440 min provide experimental indications regarding the timescale for both the beginning of amorphous CaP formation as well as the end of crystalline hydroxyl-apatite formation respectively, while the spike in the sensitization of the 110 degrees C TL peak, which was observed for immersion times ranging between 20 and 40 min, could be an experimental feature indicating the beginning of the crystalline HCAp formation.