104 research outputs found
Luminescence Data Analysis and Modeling using R
No full textThese are the R codes from the book
"Luminescence Data Analysis and Modeling Using R"
by Vasilis Pagonis
Use R! Series
Springer Nature, 202
A theoretical model for a new dating protocol for quartz based on thermally transferred OSL (TT-OSL)
No full textGroup Structural Realism
No full textWe present a precise form of structural realism, called 'group structural realism,' which identifies 'structure' in quantum theory with symmetry groups. However, working out the details of this view actually illuminates a major problem for structural realism; namely, a structure can itself have structure. This paper argues that, once a precise characterization of structure is given, the 'metaphysical hierarchy' on which group structural realism rests is seen to be overly extravagant and ultimately unmotivated
Sex, Gender, and Violent Care: An Analysis of Intersexuality and Medical Treatment
No full textDrawing upon the theories of Lisa Stevenson, Pidgeon Pagonis, and Michel Foucault, this paper examines medical jurisdiction, understandings of sex and gender, intersex conditions, and the intersex liberation movement. Gomez-Lacayo demonstrates how these concepts relate to Foucault’s theory of biopolitics and Stevenson’s conception of care. By analyzing specific cases of sexual reassignment such as that of Herculine Barbin, the author argues that treatment of intersex conditions often constitutes a violent form of care made possible through increasing medical intervention and jurisdiction. Gomez-Lacayo further analyzes medicine as a vehicle for the expression and recreation of cultural and social pluralities
Author's personal copy Optically stimulated exoelectron emission processes in quartz: comparison of experiment and theory
No full texta b s t r a c t Recent experiments have demonstrated that it is possible to measure optically stimulated exoelectron emission (OSE) signals simultaneously with optically stimulated luminescence (OSL) from quartz samples. These experiments provide valuable information on the charge movement in quartz grains. Two specific experiments measured the temperature dependence of the OSL and OSE signals on preheat and stimulation temperature. This paper provides a quantitative description of these experiments by using a previously published theoretical model for photostimulated exoelectron emission (PSEE). The experimental data yield a value of w320 1C; this process takes place with a thermal assistance energy estimated at W$(0.2970.02) eV. Good quantitative agreement is obtained between theory and experiment by assuming a thermal broadening of the thermal depletion factor for the OSL traps, described by a Gaussian distribution of energies
Thermal dependence of luminescence lifetimes and radioluminescence in quartz
No full textDuring time-resolved optical stimulation experiments (TR-OSL), one uses short light pulses to separate the stimulation and emission of luminescence in time. Experimental TR-OSL results show that the luminescence lifetime in quartz of sedimentary origin is independent of annealing temperature below 500 °C, but decreases monotonically thereafter. These results have been interpreted previously empirically on the basis of the existence of two separate luminescence centers LH and LL in quartz, each with its own distinct luminescence lifetime. Additional experimental evidence also supports the presence of a non-luminescent hole reservoir R, which plays a critical role in the predose effect in this material. This paper extends a recently published analytical model for thermal quenching in quartz, to include the two luminescence centers LH and LL, as well as the hole reservoir R. The new extended model involves localized electronic transitions between energy states within the two luminescence centers, and is described by a system of differential equations based on the Mott–Seitz mechanism of thermal quenching. It is shown that by using simplifying physical assumptions, one can obtain analytical solutions for the intensity of the light during a TR-OSL experiment carried out with previously annealed samples. These analytical expressions are found to be in good agreement with the numerical solutions of the equations. The results from the model are shown to be in quantitative agreement with published experimental data for commercially available quartz samples. Specifically the model describes the variation of the luminescence lifetimes with (a) annealing temperatures between room temperature and 900 °C, and (b) with stimulation temperatures between 20 and 200 °C. This paper also reports new radioluminescence (RL) measurements carried out using the same commercially available quartz samples. Gaussian deconvolution of the RL emission spectra was carried out using a total of seven emission bands between 1.5 and 4.5 eV, and the behavior of these bands was examined as a function of the annealing temperature. An emission band at ∼3.44 eV (360 nm) was found to be strongly enhanced when the annealing temperature was increased to 500 °C, and this band underwent a significant reduction in intensity with further increase in temperature. Furthermore, a new emission band at ∼3.73 eV (330 nm) became apparent for annealing temperatures in the range 600–700 °C. These new experimental results are discussed within the context of the model presented in this paper
Ανάπτυξη και χαρακτηρισμός ετεροεπαφών ημιαγωγών λεπτών υμενίων με ενεργειακά χάσματα Τύπου Ι και Τύπου ΙΙ για δυνητικές εφαρμογές φωτοβολταϊκών διατάξεων
No full textΕπιπρόσθετα έχει σταλεί και επιστημονικό άρθρο στο περιοδικό Thin Solid Films της Elsevier, βασισμένο στα πειραματικά αποτελέσματα αυτής της δουλειάς.We present results referring to the performances of two different thin films, one composed by two semiconductors exhibiting band alignment of Type I (straddling gap) and another on of Type II (staggered gap). The films were grown by means of a two-step process consisting in depositing first a metallic layer on silicon n-type semiconductor and subsequently oxidize it in oxygen plasma. For the type I band gap system we grow a Zr-Ti-Cu alloy, while for, the type II, we deposited metallic tin (Sn) considering that upon oxidation SnxOy, SnO SnO2 will be produced that are n,p and n type semiconductors, respectively. The grown films were analyzed by means of X-Ray Diffraction (XRD) and X-Ray Photoelectron spectroscopy (XPS) for the structural and compositional characterizations, while we used I-V four probe and photo-current measurements for the assessment of their photo-electrical performances. It came out that the systems containing semiconductors having electronic Type II band alignment perform significantly better than those of type I, suggesting that these systems could be promising for photo-electric application.Παρουσιάζουμε αποτελέσματα μελέτης αναφορικά με τις επιδόσεις δύο διαφορετικών συστημάτων λεπτών υμενίων, εκ των οποίων το ένα αποτελείται από δύο ημιαγώγιμα υλικά στα οποία η ευθυγράμμιση των ενεργειακών ζωνών τους σχηματίζουν ετεροεπαφές Τύπου Ι (straddling gap) και στο άλλο Τύπου ΙΙ (staggered gap). Τα λεπτά υμένια αναπτύχθηκαν με μια διαδικασία δύο βημάτων εκ των οποίων το πρώτο βήμα είναι η εναπόθεση με την μέθοδο της μαγνητικά υποβοηθούμενης ιοντοβολής (magnetron sputtering) ενός μεταλλικού υμενίου σε υπόστρωμα n-τύπου Si(001) και ακολούθως οξείδωση με χρήση πλάσματος οξυγόνου. Για το σύστημα της ετεροεπαφής Τύπου Ι (straddling gap) αναπτύξαμε κράμα Zr-Ti-Cu που ακολούθως οξειδώθηκε, ενώ για την ετεροεπαφή Τύπου ΙΙ (staggered gap) εναποθέσαμε μεταλλικό Sn ο οποίος κατόπιν οξείδωσης σε πλάσμα οξυγόνου παρήγαγε SnxOy , SnO και SnO2 τα οποία είναι n,p και n τύπου ημιαγωγοί αντιστοίχως. Τα αναπτυχθέντα λεπτά υμένια αναλύθηκαν ως προς την κρυσταλλική δομή με σκέδαση ακτινών-Χ (XRD) και ως προς τον στοιχειακό και χημικό χαρακτηρισμό με την μέθοδο της φασματοσκοπίας φωτοηλεκτρονίων ακτινών-Χ (XPS). Για την πρώτη εκτίμηση των φωτο-ηλεκτρικών επιδόσεων των συστημάτων λεπτών υμενίων πραγματοποιήθηκε I-V ηλεκτρικός χαρακτηρισμός με μέτρηση 4-σημείων και με μετρήσεις φωτορεύματος σε μέτρηση 2-σημείων. Αποδείχθηκε ότι τα συστήματα τα οποία εμπεριέχουν ημιαγωγούς με ετεροεπαφές Τύπου ΙΙ αποδίδουν πολύ καλύτερα σε σχέση με εκείνα που έχουν Τύπου Ι, υποδηλώνοντας ότι αυτά τα υλικά είναι πολλά υποσχόμενα για μελλοντικές φωτοηλεκτρικές χρήσεις.10
Simulations of thermally transferred OSL experiments and of the ReSAR dating protocol for quartz
No full textSublinear dose dependence of thermoluminescence as a result of competition between electron and hole trapping centers
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