published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy

published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy

No description available.

No description available.

Digitized by Kansas Correctional Industries

Hui Sze-man. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 66-69). / Text in English; abstracts in English and Chinese. / Hui Sze-man. / Abstract --- p.iii / Acknowledgement --- p.v / Table of contents --- p.vi / List of tables --- p.viii / List of Figures --- p.ix / Chapter Chapter I --- Introduction --- p.1 / Chapter Chapter II --- Thermoluminescence --- p.5 / Chapter 2.1 --- What is thermoluminescence? --- p.5 / Chapter 2.2 --- Thermoluminescence Mechanism --- p.5 / Chapter 2.3 --- Simple model by Randall and Wilkins --- p.9 / Chapter Chapter II --- I Laser induced thermoluminescence emission --- p.18 / Chapter 3.1 --- Concept of laser heating --- p.18 / Chapter 3.1.1 --- Advantages for using laser heating technique --- p.18 / Chapter 3.1.2 --- Power law heating profiles --- p.19 / Chapter 3.1.3 --- Energy transfer from laser beam to TL sample --- p.20 / Chapter 3.2 --- Zero-Dimensional for temperature profile of Thermoluminescence emission --- p.22 / Chapter Chapter IV --- Experiment and Modeling Results --- p.31 / Chapter 4.1 --- Sample Preparation --- p.31 / Chapter 4.1.1 --- Characteristics of TL material ´ؤ Lithium Fluoride (LiF) --- p.31 / Chapter 4.1.2 --- Effect of defects in LiF --- p.32 / Chapter 4.1.3 --- Sample Preparation --- p.32 / Chapter 4.2 --- TL Instrumentation and its measurements --- p.34 / Chapter 4.2.1 --- TL Instrumentation and Experimental Set-Up --- p.34 / Chapter 4.2.2 --- Measurement of sample thickness --- p.36 / Chapter 4.3 --- Laser stimulation thermoluminescence --- p.38 / Chapter 4.3.1 --- Effect of substrate on TL signal --- p.39 / Chapter 4.3.2 --- Effect of different laser's power on TL signals --- p.39 / Chapter 4.3.3 --- Effect of different irradiation duration on TL signals --- p.41 / Chapter 4.3.4 --- Effect of various sample thickness on TL signals --- p.42 / Chapter Chapter V --- Conclusion --- p.64 / Chapter 5.1 --- Conclusion --- p.64 / Chapter 5.2 --- Further Study --- p.65 / Reference --- p.66

Orientador: Keizo Yukimitu / Banca: Devaney Ribeiro do Carmo / Banca: Maria Rita Caetano Chang / Banca: Sonia Hatsue Tatumi / Banca: René Rojas Rocca / Resumo: A idade da Formação Rio Claro até o presente momento tem sido alvo de controvérsias, pois não havia sido realizado um estudo geocronológico preciso e direto. Com a utilização do quartzo como dosímetro comum aos sedimentos da formação, avaliou-se por termoluminescência que a sedimentação da Formação Rio Claro ocorreu no Pleistoceno Superior. Para garantir a veracidade dos resultados obtidos, buscou-se aprimorar a técnica de dosimetria utilizada pelo laboratório. A caracterização das propriedades luminescentes dos grãos de quartzo dos sedimentos mostrou que o sinal LOE (luminescência opticamente estimulada) de todas as amostras estava saturado e algumas das amostras também apresentavam saturação do sinal TL (termoluminescência). A saturação se deve à origem fluvial dos sedimentos que inviabilizou o desvanecimento dos sinais de TL e LOE no ato da deposição. As amostras DS 01 e DS 06 não apresentaram saturação do sinal TL. Idades TL foram obtidas para ambas possibilitando a determinação do período de deposição dos sedimentos. Os resultados obtidos mostraram que o quartzo possui dois estágios de saturação. A datação por TL utiliza apenas o primeiro estágio de saturação, pois neste a irradiação de laboratório reproduz satisfatoriamente o mesmo comportamento do sinal TL gerado na natureza / Abstract: The sedimentary deposition range of Rio Claro Formation until now remained among controversies because it was not done a precise and direct geochronological study. With the use of quartz as a common dosimeter of sedimentary formation, it was possible to evaluate using thermoluminescence that sedimentation occurred in Upper Pleistocene. To ensure the accuracy of the results obtained, It sought to improve the dosimetric technique used by the laboratory. The characterization of luminescent properties of the sedimentary quartz grains showed that OSL signal of all samples was saturated and some sample showed TL signal saturated too. Saturation is due to the sediments have fluvial origin. TL signal of the samples DS 01 and DS 06 it was saturated. The TL age was obtained for both. A study related to technical limitation TL showed that the quartz has two stages of saturation. The TL dating uses only the first stage of saturation because laboratory irradiation satisfactorily reproduces the same TL signal behavior generated in nature / Doutor

Thesis (Ph. D.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 192-198).

The potential for valid dating using feldspar minerals has recently been increasingly questioned with the recognition of a range of effects capable of giving rise to age shortfalls. The intention here was to investigate the more serious of these, and to simultaneously extend the surprisingly meagre body of knowledge on the luminescence of the feldspar minerals. A suite of feldspars representative of all major mineral species of the feldspar ternary system was assembled and mineralogically classified by XRD and SEM techniques. Characterization of some luminescence properties relevant to dating (radiation dose-sensitivities, emission spectra, thermal sensitization and bleaching by IR and green light) was conducted to enable comparison of these properties with the anomalous fading behaviour in each feldspar (IRSL and OSL intensities being subsequently measured as a function of storage duration at 10°C and 100°C). Examples of feldspars representative of each major compositional regime of the ternary system were found to fade, and similarly some were stable; no luminescence characteristics or storage duration at these temperatures permitted reliable separation of stable signals. A new method for analysis of localised transition-type anomalous fading was successfully tested on zircon; however the fading mechanism operant in feldspars was found to be tunnelling-type fading. Such fading cannot be circumvented by any feasible laboratory procedure and it was concluded that monitoring of samples for the presence of fading is essential: discovery of fading is a rejection criteria. The long-term trapping stability of the IRSL source traps was investigated by "conventional" kinetic means, and also by a combined optical and thermal approach in which the bleaching response curves of five selected feldspars were measured along with their low temperature (= 100-400 K) response. It was concluded that the IRSL signal originates from one trap type only in all feldspars, which possesses a constant ground state-to-excited state transition energy of 1.44 ± 0.01 eV. However, the excited state-to-conduction band energy varies depending on the major element composition of the feldspar. Lifetimes of microcline TL from glow curve temperatures > 300°C greatly exceed the minimum required for dating and this work and complementary experiments showed no physical basis for the existence of an age limit for coarse grain feldspars, other than dose saturation. Supplementary work supported the existence of an upper age limit of = 100 ka for fine grain materials.

Dated 1983 / Bibliography: leaves xxii-xxxii / 194, xxxii leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physics, 1964