We report the observation of optically pumped lasing in ZnO at room temperature. Thin films of ZnO were grown by plasma-enhanced molecular beam epitaxy on (0001) sapphire substrates. Laser cavities formed by cleaving were found to lase at a threshold excitation intensity of 240 kW cm−2. We believe these results demonstrate the high quality of ZnO epilayers grown by molecular beam epitaxy while clearly demonstrating the viability of ZnO based light emitting devices.

Optically pumped lasing of ZnO at room temperature

A review of quartz optically stimulated luminescence characteristics and their relevance in single-aliquot regeneration dating protocols

Distinguishing quartz and feldspar in single grain luminescence measurements

Mossbauer spectra measured by the Opportunity rover revealed four mineralogical components in Meridiani Planum at Eagle crater: jarosite- and hematite-rich outcrop, hematite-rich soil, olivine-bearing basaltic soil, and a pyroxene-bearing basaltic rock (Bounce rock). Spherules, interpreted to be concretions, are hematite-rich and dispersed throughout the outcrop. Hematitic soils both within and outside Eagle crater are dominated by spherules and their fragments. Olivine-bearing basaltic soil is present throughout the region. Bounce rock is probably an impact erratic. Because jarosite is a hydroxide sulfate mineral, its presence at Meridiani Planum is mineralogical evidence for aqueous processes on Mars, probably under acid-sulfate conditions.

https://science.sciencemag.org/content/sci/306/5702/1740.full.pdf

Jarosite and hematite at Meridiani Planum from Opportunity's Mössbauer spectrometer

Optically Stimulated Luminescence (OSL) dosimetry is attractive to the health physics and dosimetry community due to its all-optical character, fast data acquisition and the avoidance of heating the detector. Until recently there was no luminescent material sensitive enough to radiation, and at the same time suitable for stimulation with visible light, for use in this application. However, anion-deficient aluminum oxide doped with carbon (Al2O3:C) appears to be not only an extremely sensitive thermoluminescence (TL) material, but is also well-suited to OSL applications. Several OSL readout protocols have been suggested, including cw-OSL, pulsed OSL (POSL), and 'delayed' OSL (DOSL). The paper discusses the physical mechanisms that give rise to the OSL signals and the dependence of these signals upon absorbed dose. Example applications of the use of OSL from Al2O3:C in environmental radiation and ultraviolet-B dosimetry are discussed.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Optically stimulated luminescence dosimetry

A generalized mathematical description of thermally stimulated luminescence (TL) and thermally stimulated conductivity (TSC) is presented in terms of a formulation that replaces the quasiequilibrium (QE) and kinetic-order approximations by two new functions Q(T) and P(T), respectively. These functions are related and can be described in terms of the physically meaningful processes of charge trapping, release, and recombination. With the Q(T) and P(T) functions and their relations to the reaction rates, we show that slow-retrapping (first-order) processes will be dominant in systems for which QE is satisfied, and that QE and non-first-order kinetics are incompatible. We develop general expressions for TL and TSC in terms of the Q(T) and P(T) functions and arrive at analytical solutions to the rate equations for the first-order case without the QE approximation and without the presence of Q(T) in the final equations. These general first-order equations are then parametrized and compared to curve shapes generated both from the Randall-Wilkins expressions and from numerical solutions to the rate equations. We show that the general first-order equations reproduce the numerical solutions over a wider range of parameter cases than do the Randall-Wilkins equations. In addition, we suggest a simple method for the extraction of activation energies from experimental TL and TSC peaks, independent of the QE approximation.

Stephen W.S. McKeever

Papers

Analytical description of thermally stimulated luminescence and conductivity without the quasiequilibrium approximation.

Separation of quartz optically stimulated luminescence components using green (525 nm) stimulation

Optical bleaching studies of quartz

Dating of meteorite falls using thermoluminescence: application to Antarctic meteorites

Optically stimulated luminescence fluence response of Al2O3:C dosimeters exposed to different types of radiation