Treatment of zerovalent copper with NH₄X (X = I, Br or SCN) in the presence of RbI and 18-crown-6 (18c6), in acetonitrile, in air, afforded a diversity of crystalline products in which halogeno- or pseudo-halogeno-cuprate(I) anions co-precipitate with the geometrically rigid crown ether cation [Rb(18c6)]⁺. Four complexes [{Rb(18c6)}₂MeCN][Cu₄I₆] 1, [Rb(18c6)][Rb(18c6)(MeCN)₃]₂[{Rb(18c6)}₆Cu₄I₇][Cu₇I₁₀]₂2, {[Rb(18c6)][Cu₃I₃Br]}_∞3 and {[Rb(18c6)][Cu₂(SCN)₃]}_∞4 have been isolated and characterised. Formation of the copper(I) species here is believed to be an autocatalytic process catalysed by the formation of copper(II) compounds in situ. The anions present in the initial mixture have a profound effect upon metal–halogen framework formation. There is a competition between the strongly co-ordinating anions that leads to the partial or complete replacement of iodine by bromine or thiocyanate in 3 and 4, respectively. Complex 1 contains a discrete disordered [Cu₄I₆]²⁻ species sandwiched between the [Rb(18c6)]⁺ cations. The structural motif of 2 consists of ensembles of two [Rb(18c6)(MeCN)₃]⁺ and one [Rb(18c6)]⁺ cation, the bulky supramolecular cation [{Cs(18c6)}₆Cu₄I₇]³⁺ and crown-like [Cu₇I₁₀]³⁻ clusters in which seven copper atoms describe a hexagonal pyramid. In the mixed halogenocuprate(I) anion [Cu₃I₃Br]⁻ _∞ characterised in 3 all the copper atoms of the polymeric chain lie in the same plane; the halides bridge the alternate sides of the polymer. The Br atoms form bridges between [Cu₃I₃]_n chains and the [Rb(18c6)]⁺ cations. The ability of the SCN group to act as a bridge gives rise to a one-dimensional structure for 4 which contains two copper(I) atoms each with a different stereochemistry. Complexes 1, 2 and 3 display a change in emission spectrum with temperature in the solid state.

The La1 − x Ca x VO4 and La1 − x − y Eu y Ca x VO4 (0 ≤ x, y ≤ 0.2) micro/nanosized powders were prepared by aqueous nitrate–citrate sol–gel synthesis. Phase composition of the sample depends on the x and y values. The La0.9Ca0.1VO4 is crystallized in monoclinic structure up to the x = 0.1. The La0.9Eu0.05Ca0.05VO4 sample was also attributed to the monoclinic structure. Increasing concentration of europium and calcium ions in La1 − x − yEu y Ca x VO4 solid solutions leads to the change of the crystal structure, and subsequently, stabilization of the tetragonal phase takes place. The obtained samples were characterized by XRD analysis, SEM microscopy, and IR spectroscopy. Luminescence properties of the synthesized powders were studied. Emission of the La1 − x Ca x VO4 samples is weak and consists of wide bands in the 450–800 nm spectral range. The observed bands at 570 and 630 were ascribed to electron transitions in the distorted VO4 3− vanadate groups. Emission of the La1 − x − y Eu y Ca x VO4 samples consists of narrow spectral lines in the 550–730 nm spectral range. The lines are caused by the 5D0 → 7FJ electron transitions in the Eu3+ ions. The Ca2+ ions incorporation increases the intensity of the Eu3+ ions luminescence. Structure of the spectra depends on Ca2+ concentration and excitation wave length. The carried out analysis has revealed that Eu3+ ions form at least two different types of emission centers in the La1 − x − y Eu y Ca x VO4 samples. The assumption is made that type I centers are formed by the Eu3+ ions in their regular positions in the crystal lattice, while the type II centers have complex structure and consist of Eu3+ ions, Ca2+ cations, and oxygen vacancies.

The paper presents a comprehensive description of the construction features of the P66 beamline at the PETRA III storage ring as well as the experimental possibilities offered by this unique facility to the research community. The beamline is dedicated to time-resolved photoluminescence spectroscopy experiments that require high flux, high energy resolution and pulsed excitation at ultrahigh vacuum conditions. The excitation photon energies available at the beamline cover the range from 3.7 to 40 eV with two Al- and Pt-coated diffraction gratings in normal incidence geometry. Two secondary monochromators equipped with several detectors are used to register the photoluminescence signal in the spectral range from 115 to 1200 nm. The pulsed nature of the synchrotron radiation at PETRA III allows the accumulation of luminescence decay kinetics within a time interval of 192 ns (timing mode) or 16 ns (brightness mode) with a time resolution of 130 ps. Time-resolved luminescence spectroscopy studies are performed using the method of time-correlated single photon counting. The paper also reviews recent advances, as well as the most common and important scientific cases of experimental research conducted at the beamline. Plans for the future development of the beamline, along with the expansion of experimental capabilities and the implementation of additional applications of the facility, are discussed.