Optical absorption and luminescence studies of fast neutron-irradiated complex oxides for jewellery applications

We studied the optical absorption and luminescence of agate (SiO₂), topaz (Al₂[SiO₄](FOH)₂), beryl (Be₃ Al₂Si₆O₁₈), and prehnite (Ca₂Al(AlSi₃O₁₀)(OH)₂) doped with different concentrations of transition metal ions and exposed to fast neutron irradiation. The exchange interaction between the impurity ions and the defects arising under neutron irradiation causes additional absorption as well as bands' broadening in the crystals. These experimental results allow us to suggest the method for obtaining new radiation-defect induced jewellery colors of minerals due to neutron irradiation

Role of paramagnetic polyconjugated clusters in lignin antioxidant activity (in vitro)

Using physico-chemical methods (EPR, SEC, Py-GC/MS and UV/VIS spectroscopy) and wet chemical analysis, the characteristics of 6 hardwood lignins in terms of functionality, molecular weight and composition of lignin substructures were determined and considered together with the results of DPPH•, ABTS •+ and O2•- antioxidant assays with the aim to understand the relationships governing antioxidant properties of lignin. The strong positive linear correlation between lignin antioxidant capacity in the three assays used and the extent of conjugation of paramagnetic polyconjugated clusters in lignin macromolecules was found. The biological activity of the most active alkaline lignins was assessed by in vitro experiment with human blood.publishersversionPeer reviewe

Synthesis and vibration spectroscopy of nano-sized manganese oxides

The present study has been supported by the Latvian National Research Program IMIS2. One of us, IS, was supported by MES RF RFMEFI61615X0064.X-ray diffraction, micro-Raman and the Fourier transform infrared spectroscopies as well as magnetometry measurements were performed on nanosized manganese oxides to probe their phase composition and magnetic properties. It was shown that the XRD method is less sensitive to phase composition of manganese oxide samples than spectroscopic methods. While in some samples the XRD method recognised only the manganosite MnO phase, the Raman and FT-IR methods revealed additionally the presence of the hausmannite Mn3O4 phase.Ministry of Education and Science RF RFMEFI61615X0064; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

Synthesis and vibration spectroscopy of nano-sized manganese oxides

The present study has been supported by the Latvian National Research Program IMIS2. One of us, IS, was supported by MES RF RFMEFI61615X0064.X-ray diffraction, micro-Raman and the Fourier transform infrared spectroscopies as well as magnetometry measurements were performed on nanosized manganese oxides to probe their phase composition and magnetic properties. It was shown that the XRD method is less sensitive to phase composition of manganese oxide samples than spectroscopic methods. While in some samples the XRD method recognised only the manganosite MnO phase, the Raman and FT-IR methods revealed additionally the presence of the hausmannite Mn3O4 phase.Ministry of Education and Science RF RFMEFI61615X0064; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

Спектры возбуждения и фотолюминисценции твердых растворов на основе индата лантана со структурой перовскита, легированного ионами Pr3+, Nd3+, Cr3+

Excitation and photoluminescence spectra of La0,997Pr0,003InO3, La0,98Nd0,02InO3, La0,977Pr0,003Nd0,02InO3, La0,977Pr0,003Nd0,02In0,99Cr0,01O3, LaIn,099Cr0,01O3 solid solutions have been studied. It has been found that Cr+ ions incorporated into the In3++ sublattice of La0,977Pr0,003Nd0,02In0,99Cr0,01O3 solid solution can act as Nd3+ photoluminescence sensitizers under the excitation by visible light (λ = 445 nm).Исследованы спектры возбуждения и фотолюминесценции твердых растворов La0,997Pr0,003InO3, La0,98Nd0,02InO3, La0,977Pr0,003Nd0,02InO3, La0,977Pr0,003Nd0,02In0,99Cr0,01O3, LaIn0,99Cr0,01O3. Установлено, что ионы Cr3+, введенные в под-решетку ионов In3+ твердого раствора La0,977Pr0,003Nd0,02In0,99Cr0,01O3, являются сенсибилизаторами фотолюминесценции ионов Nd3+ при их возбуждении светом видимой области спектра (λ = 445 нм)