Radosław Lisiecki

The Ni-doped Li₂B₄O₇ (Li₂O–2B₂O₃) glass was prepared by the conventional melt-quenching method. Structural and spectroscopic properties of the glass were investigated using X-ray diffraction (XRD), optical absorption, and photoluminescence spectroscopy, including excitation, emission, and decay kinetics. The absence of sharp diffraction peaks in the XRD pattern confirms the disordered glassy structure of the investigated glass. The optical absorption spectrum shows three broad bands associated with spin-allowed transitions of Ni²⁺ (3d⁸) ions. The excitation and emission spectra of the Li₂B₄O₇:Ni glass reveal several spin-allowed and spin-forbidden 3d–3d transitions of Ni²⁺ ions. In particular, the Li₂B₄O₇:Ni glass exhibits broad green and red emissions centred at approximately 525 and 687 nm, respectively, as well as weak near-infrared emission bands in the 900–1100 and 1500–1750 nm regions. The analysis of the crystal field splitting for Ni²⁺ ions in the Li₂B₄O₇:Ni glass is carried out, and the Racah parameters (B and C) and the crystal field strength (Dq) are calculated. The Tanabe–Sugano diagram for the octahedrally coordinated Ni²⁺ ions in the Li₂B₄O₇:Ni glass is built and discussed.

Pr3+-doped oxyfluoride glasses with the composition 45(1-x)SiO2–25Al2O3–20Na2CO3–10CaF2–xPr2O3 were synthesized by the conventional melt-quenching method and investigated with respect to their structural, optical and upconversion properties. The glasses exhibited high optical quality, excellent transparency (~90% in the visible range), and an optical band gap of 4.78 eV for the undoped sample. Photoluminescence measurements revealed characteristic emissions from the 3P0 and 1D2 excited states of Pr3+ ions. Efficient excitation in the blue spectral region enables pumping with commercially available blue LEDs and laser diodes. Temperature-dependent lifetime studies demonstrated stronger quenching of the 1D2 level than the 3P0 state. Under 444 nm excitation, ultraviolet upconversion emission (250–310 nm) assigned to 5d1→4f2 transitions was observed via a two-photon process. The coexistence of efficient visible downconversion and UV upconversion highlights the multifunctionality of these glasses, making them promising for spectral conversion, remote phosphors, photonic devices, and hybrid photocatalytic systems.

Two new nitropyridine amino N-oxide derivatives were synthesized and characterized: 3-N-methylamino-4-nitropyridine N-oxide (NOPCH₃) and [(4-nitropyridine-3-yl)amino]propanoic acid N-oxide (NOPCOOH)1. Their molecular and crystal structures were determined by single-crystal X-ray diffraction, and the intermolecular contact patterns were evaluated using Hirshfeld surface analysis. Vibrational properties were investigated by FT-IR and Raman spectroscopy and interpreted with the support of quantum-chemical calculations (DFT). Electronic absorption was examined by UV–Vis measurements, while photoluminescence spectra and decay profiles were recorded under femtosecond excitation and interpreted conservatively in terms of relaxed excited-state emission. Solid-state ¹³C CP-MAS and ¹H WPMLG NMR spectroscopy provided additional support for the chemical constitution of both derivatives, with ¹H spectra interpreted conservatively because of the limitations inherent to solid-state homonuclear-decoupled measurements. A comparative analysis shows that replacing the methyl substituent (NOPCH₃) with the carboxylic-acid side chain (NOPCOOH) modifies the hydrogen-bonding landscape and the local electronic environment of the NO₂ group, which is reflected in the positions and intensities of selected NO₂-related vibrational bands and in the near-UV electronic transitions. Overall, the combined structural and spectroscopic dataset provides a consistent structure–property picture for both N-oxide derivatives and a basis for further studies of their coordination and photophysical behavior.

Pr3+-doped oxyfluoride glasses with the composition 45(1-x)SiO2–25Al2O3–20Na2CO3–10CaF2–xPr2O3 were synthesized by the conventional melt-quenching method and investigated with respect to their structural, optical and upconversion properties. The glasses exhibited high optical quality, excellent transparency (~90% in the visible range), and an optical band gap of 4.78 eV for the undoped sample. Photoluminescence measurements revealed characteristic emissions from the 3P0 and 1D2 excited states of Pr3+ ions. Efficient excitation in the blue spectral region enables pumping with commercially available blue LEDs and laser diodes. Temperature-dependent lifetime studies demonstrated stronger quenching of the 1D2 level than the 3P0 state. Under 444 nm excitation, ultraviolet upconversion emission (250–310 nm) assigned to 5d1→4f2 transitions was observed via a two-photon process. The coexistence of efficient visible downconversion and UV upconversion highlights the multifunctionality of these glasses, making them promising for spectral conversion, remote phosphors, photonic devices, and hybrid photocatalytic systems.

Pr3+-doped oxyfluoride glasses with composition 45(1-x) SiO2-25 Al2O3-20 Na2CO3-10 CaF2-x Pr2O3 were synthesized by the conventional melt-quenching technique and systematically investigated in terms of their structural, spectroscopic and upconversion properties. The prepared glasses exhibited high optical quality and excellent transparency, reaching approximately 90% transmittance in the visible spectral range. The optical band gap of the undoped glass was determined to be 4.78 eV. Photoluminescence studies revealed characteristic Pr3+ emissions originating from the 3P0 and 1D2 excited states. The strongest luminescence was observed for the sample containing 0.1 mol% Pr3+, whereas increasing dopant concentration resulted in progressive concentration quenching. Excitation spectra demonstrated efficient absorption in the blue spectral region, indicating the suitability of these materials for excitation by commercially available blue laser diodes and LEDs. Time-resolved measurements revealed significantly stronger concentration- and temperature-induced quenching of the 1D2 level compared with the 3P0 state, whose decay dynamics remained nearly temperature independent. A remarkable feature of the developed glasses is their ability to convert blue light into ultraviolet radiation. Upon 444 nm excitation, ultraviolet upconversion emission in the 250–310 nm range, assigned to 5d1→4f2 transitions of Pr3+ ions, was observed. Analysis of the pump-power dependence yielded a slope of 1.7, indicating a two-photon upconversion process involving the 1D2 level as an intermediate state. The coexistence of intense visible downconversion and efficient UV upconversion within a single amorphous host demonstrates the unique multifunctionality of the investigated materials. These findings identify Pr3+-doped oxyfluoride glasses as promising candidates for spectral conversion systems, remote phosphors and advanced photonic devices operating across a broad spectral range.