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

Characterization of the pre-dose effect using ESR and TL

Concepts and approaches to in situ luminescence dating of Martian sediments.

Optically stimulated luminescence (OSL) properties of dental enamel are discussed with a view to the development of an in vivo dose assessment technique for medical triage following a radiological/nuclear accident or terrorist event. In the OSL technique, past radiation exposure is assessed by stimulating the sample with light of one wavelength and monitoring the luminescence at another wavelength, under the assumption that the luminescence originates from the recombination of radiation-induced charges trapped at metastable defects in the enamel and that the intensity of the luminescence signal is in proportion to the absorbed radiation dose. Several primary findings emerged from this research: (a) sensitivities varied considerably between different teeth and also between fragments of the same tooth, (b) OSL signals were found to decay rapidly during the first 12 h after irradiation and more slowly afterward, (c) the fading rate of the luminescence signal varied between fragments, and (d) blue light stimulation yields greater sensitivity than infra-red stimulation, while the OSL signal obtained with a high-intensity pulsed green-light laser was found not to be correlated with the radiation dose. Significant challenges remain to developing a practical in vivo technique, including the development of calibration procedures and lowering minimum detectable doses.

Stephen W.S. McKeever

Papers

Characterization of the pre-dose effect using ESR and TL

Concepts and approaches to in situ luminescence dating of Martian sediments.

Optically Stimulated Luminescence (OSL) of Tooth Enamel and its Potential Use in Post-Radiation Exposure Triage

Point Defects and the Pre-Dose Effect in Quartz

Models for optical bleaching of thermoluminescence in sediments