Ionizing radiation applied on food eliminates harmful microorganisms, prevents sprouting and delays ripening. All methods for detection of irradiated food are based on physical, chemical, biological or microbiological changes caused by the treatment with ionizing radiation. When minerals are exposed to ionizing radiation, they accumulate radiation energy and store it in the crystal lattice, by which some electrons remain trapped in the lattice. When these minerals are exposed to optical stimulation, trapped electrons are released. The phenomenon, called optically stimulated luminescence or photostimulated luminescence, occurs when released electrons recombine with holes from luminescence centers in the lattice, resulting in emission of light with certain wavelengths.

In this paper, the results of measurements performed on seven different samples of herbs and spices are presented. In order to make a comparison between luminescence signals from samples treated with different doses, unirradiated samples are treated with Co-60 with doses of 1 kGy, 5 kGy and 10 kGy. In all cases it was shown that the higher the applied dose, the higher the luminescence signal.

In this study, Strontium Bismuth Niobate (SrBi2-xTmxNb2O9 with 0 ≤ x ≤ 0.1) doped by Tm was synthesized using by the hydrothermal method. The microstructure and electrical properties were mainly investigated. XRD analysis showed a single-phase orthorhombic structure for Tm-doped SrBi2Nb2O9 samples. The crystallite size is anisotropic and the strain is apparently independent of Tm amount. Dielectric properties for doped SrBi2Nb2O9 with Tm3+ ion have the same trend discussed for the pure sample. FTIR resulats showed that NbO6 octahedral is formed, on one hand, and on the other hand, it shows that spectras for doped and undoped samples are nearly the same. The Cross-section of ceramics showed the plate-like morphology, also the distribution of the pore in ceramics are observed for all samples. Tm dopants produce only minor changes in the impendence parameter values at room temperature. The luminescent (PL) properties of Tm-doped SrBi2Nb2O9 ceramic powders were investigated. The optimum Tm3+ concentration for the maximum PL intensity was found to be at x = 0.075.

Photoluminescence of HgCdTe epitaxial films and nanostructures and electroluminescence of InAs(Sb,P) light-emitting diode (LED) nanoheterostructures were studied. For HgCdTe-based structures, the presence of compositional fluctuations, which localized charge carriers, was established. A model, which described the effect of the fluctuations on the rate of the radiative recombination, the shape of luminescence spectra and the position of their peaks, was shown to describe experimental photoluminescence data quite reasonably. For InAs(Sb,P) LED nanoheterostructures, at low temperatures (4.2–100 K) stimulated emission was observed. This effect disappeared with the temperature increasing due to the resonant ‘switch-on’ of the Auger process involving transition of a hole to the spin-orbit-splitted band. Influence of other Auger processes on the emissive properties of the nanoheterostructures was also observed. Prospects of employing II–VI and III–V nanostructures in light-emitting devices operating in the mid-infrared part of the spectrum are discussed.

Luminescence dating is based mainly on the dosimetric properties of quartz and feldspar. These minerals are among the most popular found on Earth, resulting in the possibility of using luminescence methods in practically any environment. Currently, quartz remains the best recognized mineral in terms of dosimetric properties, particularly with regards to results obtained for quartz grains, which are regarded as being the most reliable in luminescence dating. Supporters of luminescence methods are constantly growing, however, these groups do not always have sufficient knowledge to avoid even the most basic of issues that may be encountered overall – from the process of sampling through to the awareness of what a single luminescence result represents. The present paper provides an overview of several practical aspects of luminescence dating such as correct sampling procedures and all necessary information regarding the calculation of the dose rate and equivalent dose with particular reference to potential problems that occur when the age of the sample is being determined. All these aspects are crucial for obtaining a reliable dating result, on the other hand, they remain a potential source of uncertainty.

The Ag₈SnSe₆ argyrodite compound was synthesized by the direct melting of the elementary Ag, Sn and Se high purity grade stoichiometric mixture in a sealed silica ampoule. The prepared polycrystalline material was characterized by the X-ray diffraction (XRD), visible (VIS) and near-infrared (NIR) reflection and photoluminescence (PL) spectroscopy. XRD showed that the Ag₈SnSe₆ crystallizes in orthorhombic structure, Pmn2₁ space group with lattice parameters: а = 7.89052(6) Å, b = 7.78976(6) Å, c = 11.02717(8) Å. Photoluminescence spectra of the Ag₈SnSe₆ polycrystalline wafer show two bands at 1675 nm and 1460 nm. Absorption edge position estimated from optical reflectance spectra is located in the 1413–1540 nm wavelength range.

The article presents an overview and a classification of X-ray detection methods. The main motivation for its preparation was the need to select a suitable and useful method for detecting signals from a currently developed miniature micro-electro-mechanical system (MEMS) X-ray source. The described methods were divided into passive and active ones, among which can be distinguished: chemical, luminescent, thermo-luminescent, gas ionization, semiconductor, and calorimetric methods. The advantages and drawbacks of each method were underlined, as well as their usefulness for the characterisation of the miniature MEMS X-ray source.

Optically stimulated luminescence (OSL) and thermoluminescence (TL) methods are commonly used in dosimetry of ionizing radiation and dating of archaeological and geological objects. A typical disadvantage of OSL detectors is signal loss over a longer time scale. In this article, we present a method of studying this phenomenon as well as monitoring the state of the detector by means of optical sampling. The method was used to determine the OSL signal loss (fading) characteristics of selected potassium feldspars.

Tris(8-hydroxyquinoline)aluminium with poly(N-vinylcarbazole) (Alq ₃:PVK) or polystyrene sulfonate (Alq ₃:PSS) were deposited by spin-coating on glass and silicon substrates. SEM measurements show that relatively smooth thin films were obtained. Fourier transform infrared measurements were performed to confirm the composition of the samples. The optical properties of thin films containing Alq ₃:PVK and Alq ₃:PSS were characterised using absorption spectroscopy and spectroscopic ellipsometry. It was found that the absorption spectrum of Alq ₃:PVK is characterised by four bands, while for Alq ₃:PSS only three bands are visible. The photoluminescence of the studied thin layers shows a peak with a maximum at about 500 nm. Additionally, cyclic voltammetry of Alq ₃ is also presented. Theoretical density functional theory calculations provide the insight into the interaction and nature of Alq ₃:PVK and Alq ₃:PSS excited states. Finally, the organic light-emitting diode (OLED) structure based on Alq ₃:PVK was fabricated and showed strong electro-luminescence with a green emission at 520 nm. The results of the device show that the ITO/PEDOT:PSS/Alq ₃:PVK/Ca/Al system can be useful for the production of low-cost OLEDs with Alq ₃:PVK as an active layer for future lighting applications.

In the paper the analysis of up-conversion (UC) luminescence in 0.5Yb₂O₃/(0.25-1)Eu₂O₃ (mol.%) co-doped germanate glass and optical fibre has been investigated. Up-conversion emission of bands at 591, 616, 652, 701 nm to which correspond Eu³⁺: ⁵D₀ → ⁷F₁, ⁵D₀ → ⁷F₂, ⁵D₀ → ⁷F₃, ⁵D₀ → ⁷F₄ transitions, respectively was obtained as a result of cooperative energy transfer between Yb³⁺ and Eu³⁺ ions. The highest up-conversion emission (Yb³⁺ → Eu³⁺ energy transfer efficiency η = 24%) was obtained in 0.5Yb₂O₃/0.75Eu₂O₃ co-doped glass. Comparison of up-conversion and down-conversion luminescence spectra of bulk glass, glass fibre and different length double-clad optical fibre (up to 5 m) showed subtle differences in shape of the spectrum. In comparison to down – conversion emission (λ_exc = 405 nm) main UC luminescence band is red-shifted by 2 nm and is characterized by 5 nm greater full – width half – maximum (FWHM).