Thermoluminescence measurements

Thermoluminescence measurements on a few milligrams of material scraped from fired-clay objects, such as pottery and figurines, can readily establish whether objects made of these materials are genuine antiquities, recent copies, or fakes. Chemical tests on what appeared to be a broken and restored terracotta statuette, purporting to be of Etruscan origin (from... 

Those whose research interests involve the examination of trace element distribution in ceramic materials as an indication of provenance and those making thermoluminescence measurements will find few useful clay samples among the materials preserved by archaeologists. Thus, a potentially valuable source of documented clay materials is lost when unbaked clay tablets are routinely fired and cleaned without systematic sorting to preserve in their original state those specimens which do not require firing for their survival. 

This mechanism takes into account volatile and chain scission yields, the radicals identified by ESR and the results of charge scavenging and recombination obtained by absorption spectroscopy at low temperatures and thermoluminescence measurements. 

Thermoluminescence measurements were also made on X-ray and 7-ray irradiated KN3 from 47 to 255°K, yielding activation energies and pre-exponential factors [74,75]. Because the heating rates are different from those used for the UV-irradiated KN3, it is difficult to relate the two sets of data. Since thermoluminescence is sensitive to impurity content, there are also problems in relating studies on crystals grown in different laboratories. However, Townsend et al. [74,75] determined pre-exponential factors which have also been obtained from kinetic studies of the decay of ESR and optical spectra, enabling a comparison with determinations from annealing studies of ESR and optical bonds. In X-ray... 

Lipid dispersions were prepared by sonication of a dry film of lipid in 1 mM dodecylmaltoside, added to the D1-D2 complex in a small volume of buffer containing the same detergent, incubated for 2 min at 20 C and diluted twentyfold in buffer without detergent. Centrifugation of samples was at 350,000 xg for 20 min, 4 C and assay of electron transfer by reduction of dichlorophenol-indophenol (DCPIP) in the presence of diphenylcarbazide (DPC) was as in reference 10, in 50 mM Tris pH 8.5. Thermoluminescence measurements were made with 5 //g chlorophyll of the D1-D2 preparation in 0.5 ml 50 mM HEPES pH 7.5 according to reference 17. 

Secondary photosynthetic electron transfer was detected after addition of artificial electron acceptors and donors, including a quinone dependent activit y on adding decylplastoquinone. An equivalent activity was obtained on addition of the much more hydrophobic plastoquinone-9 molecule but only when a reconstitution procedure was adopted in which a diacyl glycerolipid extract of thylakoids was used. Thermoluminescence measurements showed that reconstitution with plasto-quinone-9 and lipid involved the binding of the quinone to some of the reaction centres in a preparation. Thus a limited reconstitution of quinone-reaction centre interactions could be achieved without proteins other than those already present in the isolated reaction centre. 

Thermoluminescence measurements observing crystal defects in, e.g., quartz grains being as impurity on the surface of some foods (vegetables) can also be successfully applied (Farkas 2004). Another standardized method is based on the irradiated fat-containing foods using the mass-spectrometric detection 2-alkyl-cyclobutanones after gas chromatographic separation O Fig. 23.17 (Delincee 2002). 

In thermoluminescence dating, a sample of the material is heated, and the light emitted by the sample as a result of the de-excitations of the electrons or holes that are freed from the traps at luminescence centers is measured providing a measure of the trap population density. This signal is compared with one obtained from the same sample after a laboratory irradiation of known dose. The annual dose rate for the clay is calculated from determined concentrations of radioisotopes in the material and assumed or measured environmental radiation intensities. 

Trace-element analysis of metals can give indications of the geographic provenance of the material. Both emission spectroscopy (84) and activation analysis (85) have been used for this purpose. Another tool in provenance studies is the measurement of relative abundances of the lead isotopes (86,87). This technique is not restricted to metals, but can be used on any material that contains lead. Finally, for an object cast around a ceramic core, a sample of the core material can be used for thermoluminescence dating. 

Zimmerman, D. W., M. P. Yuhas, and P. Meyers (1974), Thermoluminescence authenticity measurements on core material from the bronze horse of the New York Metropolitan Museum of Art, Archaeometry 16, 19-30. 

The origin of this lack of uniqueness has been traced to the fact that both TSC and thermoluminescence are only indirect trap-spectroscopic methods. In contrast to TSCAP techniques, the thermal release from traps or the capture of charge carriers in traps is not measured directly. 

These analyses require that the 10) values for normal incidence be modified for irradiation geometries where the field is incident other than perpendicular to the surface of the personal monitor. The methods used in developing these modifications to fl pdO) for nonnormal incidence included extensive Monte Carlo calculations of photon interactions in anthropomorphic phantoms (Xu, 1994) or in PMMA and tissue slabs and the ICRU sphere (Grosswendt, 1991 Grosswendt and Hohlfeld, 1982), and thermoluminescent dosimeter measurements in water cubes (Lakshmanan et al., 1991). Some of these modifications for /fp(lO) are presented in ICRU (1992). 

The current situation is exemplified by a study of clinical staff exposures in cardiac angiography at the Montreal Heart Institute (Renaud, 1992). Extensive measurements of staff exposures were made using thermoluminescent dosimeters (TLDs) for 15,000 procedures in three cardiac catheterization laboratories over a 5 y period (1984 to 1988). The TLDs were located under the protective apron at the waist and at the collar outside and above the apron. Readings were made at three-month intervals, with a minimum reportable value of 0.2 mSv. Average values (in mSv per y) for various groups of staff, based on measurements with TLDs worn at the collar, are given in Table 3.3. 

Archaeologists have long sought methods for obsidian characterization that were rapid, reliable, non-destructive, and low-cost. Among the various methods investigated were visual techniques (79), density measurements (20), magnetic properties (27), thermoluminescence (22), fission-track analysis (25), Mossbauer spectroscopy (24), and natural radioactivity (25). Although some of the methods occasionally identified differences between sources, the overlap between sources was such that their overall reliability was unsatisfactory. The most successful method of characterization for obsidian provenance research has been compositional analysis (26). 

Physical Principles of Thermoluminescence and Recent Developments in its Measurement ,... 

Figure 10 shows the schematic illustration of the sintered layer-type sensor chip. The catalyst powder is ground using an auto-grinder and only fine particles are selected using a mesh filter. When the rare-earth ion is doped into the catalyst, an aqueous solution of rare-earth salt (e.g., (Dy(N03)3) is mixed in and then the catalyst is calcined. The rare-earth-activated phosphors used for thermoluminescence (TL) measurements, e.g., BaSO Eu, CaSO Eu, and SrSO Eu, also act as CTL catalysts. 

The final hydromagmatic phase occurred from several explosion craters mainly located in the western sector of the volcano, and produced about 1 km3 of pyroclastic surge, flow and lahar deposits and very few lavas. The best known explosion craters include the maars of Nemi and Albano lakes. The youngest measured age, obtained by thermoluminescence methods on wet pyroclastic flow deposits from the Albano crater, yields a date of about 19 ka (Voltaggio and Barbieri 1995 and references therein). 

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