Trap Parameters for the Fast OSL Signal Component Obtained through Analytical Separation for Various Quartz Samples.

Trap stability is essential in luminescence dating and thermochronometry. Trap depth and frequency factors determining the stability of the fast component of optically stimulated luminescence (OSL) in quartz, which is the most important in dating, have yet to be uniquely determined, especially for samples with an OSL signal not dominated by this component. One can determine them in OSL thermal depletion curve (OTDC) experiments. The separation of the fast OSL signal undisturbed by other OSL components is vital for obtaining accurate parameters for the traps of interest. This work presents a method of simultaneous thermal and optical stimulation using red light (620 nm) to separate the fast OSL component (the thermally modulated OSL method-TM-OSL). The OTDC experiment with the TM-OSL stimulation was used for the trap parameter determination on a variety of quartz samples, leading us to report for the first time, the trap parameters for the fast OSL component analytically separated in quartz from rock samples. The results obtained for these samples with the fast component of low intensity are consistent with those with an intensive fast OSL component. Results of OTDC measurements for all investigated quartz samples were tested for a wide range of irradiation doses.

Study of persistent luminescence and thermoluminescence in SrSi2N2O2:Eu2+,M3+ (M = Ce, Dy, and Nd).

The process of persistent luminescence or glow-in-the-dark, the delayed emission of light of irradiated substances, has long fascinated researchers, who have made efforts to explain the underlying physical phenomenon as well as put it to practical use. However, persistent luminescence is an elusive and difficult process, both in terms of controlling or altering its properties, as well as providing a quantitative description. In this paper, we used SrSi2N2O2:Eu2+ as a model persistent phosphor, characterized by the broad distribution of structural defects and exhibiting long-lasting Eu2+ luminescence that is visible for a few minutes after switching off UV light. We investigated the persistent luminescence process by two complementary methods, namely, thermoluminescence and temperature-dependent persistent luminescence decay measurements. Analysis of experimental data allowed us to determine the depth distribution of traps, and allowed us to distinguish two different mechanisms by which the emission is delayed. The first, the temperature-dependent mechanism, is related to trap activation, while the second, temperature-independent mechanism is related to carrier migration. Finally, we employed the strategy of the co-doping of the phosphor SrSi2N2O2:Eu2+,M3+ (M = Ce, Nd, Dy) to modify the persistent luminescence properties.

OSL CHARACTERISTICS: THEORY AND EXPERIMENTS.

Fundamental effects such as the participation of crystal lattice vibrations should be taken into account while considering photo-ionisation in solids at measurement temperatures characteristic for dosimetric applications. The impact of these effects on the optically stimulated luminescence (OSL) can be recognised for example by changes in the optical cross-section of the trap with the stimulation energy and the temperature. The OSL signal observed during the stimulation with variable energy, during the linear heating of a sample or during the stimulation with modulation of the shape of a spectral band can provide important information about the properties of the trap. Moreover, such methods when applied with carefully selected experimental parameters enable the effective separation of the OSL signal originating from different traps. The consequences of such an approach to optical stimulation will be presented using the modelling of the OSL process and compared with experimental results.