Luminescence of sapphire single crystals irradiated with high-power ion beams

Optical absorption, photo- and cathodoluminescence of a sapphire single crystal (α-Al 2 O 3 ) exposed to pulsed nanosecond radiation with high-power ion beams C + /H + with an energy of 300 keV and energy density 0.5-1.5 J/cm 2 were first investigated in this work. It was found that under ion irradiation accompanied by heating of sapphire up to melting, the formation of F-type centers and their aggregates associated with oxygen vacancies was observed in the crystals under study. These centers have luminescence bands at 330, 410 and 500 nm which depend on the type and wavelength of the optical excitation. The appearance of a new PL emission at 435 nm, presumably associated with a complex vacancy-impurity defect, was also observed in the photoluminescence spectra. © Published under licence by IOP Publishing Ltd.The work was supported by the initiative scientific project № 16.5186.2017/8.9 of the Ministry of Education and Science of the Russian Federation. Experiments on ion irradiation of sapphire was done at the KIPT as a part of the state task

Self-assembled monolayers of alendronate on Ti6Al4V alloy surfaces enhance osteogenesis in mesenchymal stem cells

Phosphonates have emerged as an alternative for functionalization of titanium surfaces by the formation of homogeneous self-assembled monolayers (SAMs) via Ti-O-P linkages. This study presents results from an investigation of the modification of Ti6Al4V alloy by chemisorption of osseoinductive alendronate using a simple, effective and clean methodology. The modified surfaces showed a tailored topography and surface chemistry as determined by SEM microscopy and RAMAN spectroscopy. X-ray photoelectron spectroscopy revealed that an effective mode of bonding is created between the metal oxide surface and the phosphate residue of alendronate, leading to formation of homogenous drug distribution along the surface. In-vitro studies showed that alendronate SAMs induce differentiation of hMSC to a bone cell phenotype and promote bone formation on modified surfaces. Here we show that this novel method for the preparation of functional coatings on titanium-based medical devices provides osseoinductive bioactive molecules to promote enhanced integration at the site of implantation

Thermoluminescence of Magnesium Oxide Ceramics Obtained by the Method of Electron Beam Synthesis

The luminescent properties of MgO ceramics synthesized by the electron beam method were investigated. The luminescence centers were identified in the samples. The TL curves and dose characteristics of TL peaks excited by a pulsed electron beam (130 keV, 1.5–60 kGy) were analyzed

Luminescent Properties of Nanostructured Al2O3 Ceramics Irradiated with C+/H+ Pulsed Ion Beams

The luminescent properties of nanostructured α-Al2O3 ceramics irradiated with C+/H+ pulsed ion beams have been studied. The relationship between changes in the TL properties of ceramics and the formation of radiation defects under irradiation is discussed

CATHODO- AND THERMOLUMINESCENCE OF α-Al2O3 SINGLE CRYSTALS IRRADIATED WITH Fe10+ PULSED ION BEAM

PCL and TL of α-Al2O3 single crystals irradiated with various doses of Fe10+ pulsed ion beam were studied. The formation of F-type centers in irradiated crystals was observed. A similar nonmonotonic dependence of PCL of F-centers and TL on the value of the radiation dose was found

Thermodynamic characteristics of ternary sulfides MLn₂S₄ and solid solutions thereof

Thermodynamic characteristics of ternary sulfides MLn₂S₄ and soiid solutions thereof have been determined by EMF method in various modifications. The research results have shown that solid electrolytes CaGd₂S4 and BaTm₂S4 are stable compounds within the electrolytic range 653-723 K. The simultaneous determination of the binary sulfide activity in ternary BaTm₂S₄, CaY₂S₄, CaSm₂S₄, CaPr₂S₄ systems and of the cation and anion transfer numbers allowed us to estimate the phase stability limits and to propose a vacancy mechanism of defect formation and suggest the predominantly sulfide-ion type conductivity in the solid electrolytes studied.Методом ЭДС в различных модификациях определены термодинамические характеристики тернарных сульфидов MLn₂S₄ и твердых растворов на их основе. Проведенные исследования позволили считать твердые электролиты CaGd₂S4 и BaTm₂S4 устойчивыми соединениями в электролитическом интервале 653—728 К. Одновременное определение активности бинарных сульфидов в тернарных BaTm₂S₄, CaY₂S₄, CaSm₂S₄, CaPr₂S₄ и катионных и анионных чисел переноса сделало возможным оценить границы устойчивости фаз. предложить вакансионный механизм дефектообразования и преимущественно сульфид-ионный тип проводимости в исследуемых твердых электролитах.Методом ЕДС у різних модифікаціях виявлено термодинамічні характеристики тернарних сульфідів MLn₂S₄ і твердих розчинів на іх основі. Проведені дослідження дозволили вважати тверді електроліти CaGd₂S4 і BaTm₂S4 стійкими сполуками в електролітичному інтервалі 653-723 К. Одночасне виявлення активності бінарних сульфідів в тернарних BaTm₂S₄, CaY₂S₄, CaSm₂S₄, CaPr₂S₄, а також катіонних і аніонних чисел переносу зробило можливим оцінити межі стійкості фаз, запропонувати вакансійний механізм дефектоутворення і переважно сульфід-іонний тип провідності у твердих електролітах, що досліджувалися

Influence of Molecular Structure on the Rate of Intersystem Crossing in Flexible Biradicals

Laser flash photolysis (LFP), low-field chemically induced dynamic nuclear polarization (CIDNP), and time-resolved electron paramagnetic resonance (TREPR) techniques have been used for the comparative study of magnetic field and spin effects in acyl−ketyl and bis(ketyl)biradicals formed during the photolysis of 2-hydroxy-2,12-dimethylcyclododecanone (1-OH) and 2,12-dihydroxy-2,12-dimethylcyclododecanone (2-OH), respectively. The short biradical lifetime, the small magnetic field effect (MFE) on a biradical lifetime, and the low intensity of spin-correlated radical pair (SCRP) polarization observed during the photolysis of 1-OH indicate that the main channel of intersystem crossing in acyl−ketyl biradical is spin−orbit coupling (SOC). For bis(ketyl) biradicals observed during the photolysis of 2-OH, SOC is of minor importance, and both MFE and SCRP polarization are much larger. It is shown that the presence of significant SOC in biradicals can result in an increase of the CIDNP intensity at low magnetic fields. Calculations of biradical evolution, based on the numerical solution of the stochastic Liouville equation (SLE), were carried out by taking into account (1) the molecular dynamics of the polymethylene chain linking the radical centers, (2) the distance-dependent exchange interaction, (3) the chemical reactions of the biradical, (4) the spin relaxation processes, and (5) state-to-state transitions caused by hyperfine interaction and SOC. A common set of parameters was found which allows quantitative description of the field dependence of the biradical lifetime, the CIDNP field dependence, and the TREPR spectra and kinetics