Kinetic analysis of thermoluminescence glow curves in feldspar: evidence for a continuous distribution of energies

Abstract

Abstract:The thermoluminescence (TL) glow curves from feldspars have been the subject of numerous studies, because of their importance in luminescence dating and dosimetry. This paper presents new experimental TL glow curves in a plagioclase feldspar, measured using the T max -T stop technique of glow curve analysis. Kinetic analysis of the experimental results is carried out for a freshly irradiated sample, as well as for a sample which has undergone optical treatment using infrared light for 100 s at 50°C. Application of the initial rise method of analysis indicates that the TL signals from both samples can be characterized by a continuous distribution of energy levels. By subtracting the TL glow curves measured at successive T stop values, a series of TL glow curves is obtained which are analyzed using the empirical general order kinetics. It is found that all TL glow curves obtained by this subtractive procedure can be described accurately by the same general order parameter b ~1.7. In a second attempt to analyze the same TL glow curves and possibly extract information about the underlying luminescence process, the shape of TL glow curves is analyzed using a recently proposed physical kinetic model which describes localized electronic recombination in donor-acceptor pairs. Within this model, recombination is assumed to take place via the excited state of the donor, and nearest-neighbor recombinations take place within a random distribution of centers. This recent model has been used recently to describe successfully several types of luminescence signals. This paper shows that it is possible to obtain good fits to the experimental data using either one of these two approaches.

Evidence of shallow TL peak contributions in infrared radiofluorescence

“…There might be a trap, around ~ 0.3 eV and 0.78 ± 0.09 eV. This is similar to observations reported by Kirsh et al (1987) and Pagonis et al (2014), by measuring the red TL emission of microcline.…”

Mathematical characterization of continuous wave infrared stimulated luminescence signals (CW-IRSL) from feldspars

“…Sfamba et al [32] analyzed isothermal luminescence signals from Durango apatite, and found that these signals could be fitted very accurately with the model of Jain et al [22]. Also Pagonis et al [33, submitted] analyzed experimental CW-IRSL curves from 24 different types of feldspars by using the analytical equation (8) Pagonis et al [34] analyzed TL glow curves from feldspar using the model of Jain et al [22], as well as using the general order kinetics model of TL.…”

“…The process is then repeated several times by irradiating the same aliquot with the same dose and heating to a slightly higher temperature T stop each time, in steps of 10°C for the complete interval T stop =50-380 o C. This procedure produces a series of TL glow curves which were analyzed in Pagonis et al [34], as well as a series of CW-IRSL curves which are the subject of the study in this paper. Figure 3a shows the result of fitting a typical CW-IRSL curve from sample FL3 (measured at 50 o C) using equation (8).…”

“…The IR bleaching was achieved by IR LEDs (870 ± 40 nm) and the luminescence emission was detected using a photomultiplier tube and combination of optical filters transmitting photons in the wavelength region 395 ± 50 nm. The experimental procedure used in this paper is described in a separate experimental study of the effect of a thermal cleaning process on the TL glow curves for this sample (Pagonis et al [34]). Specifically the TL glow curves are obtained using a T max -T stop thermal cleaning procedure, as follows.…”

“…Accurate mathematical characterization of the shape of these signals in feldspars is also of importance in connection with "anomalous fading" of luminescence signals in dating studies ( [4][5][6][7]; and references therein). Several studies have suggested that anomalous fading is due to quantum mechanical tunneling from either the ground state or from the excited state of the trap, and that this ground state tunneling process in various materials can be described by power-law decay ([4]- [34]). …”