Influence of metal ions on the response of solvatochromic Reichardt indicators: NMR spectroscopic study

Association of Mg²⁺ and La³⁺ ions with Reiсhardt betaine dyes in deuterated DMSO has been studied using ¹H-NMR method. Basing on chemical shifts of the betaine protons in the presence of metal ions as well as on the chemical shifts of the protonated betaine protons, the Mg²⁺ and La³⁺ ions interaction with the dye molecule has been concluded to be of acid-base nature. The data obtained suggest the inadmissibility of the betaine acid-base sensors in the presence of multicharged metal ions.Асоцiацiю iонiв Mg²⁺ i La³⁺ з бетаїновими барвниками Райхардта у дейтерированому DMSO дослiджена з застосуванням метода ПМР. На пiдставi значень хiмiчних зсувiв протонiв бетаїну у присутностi iонiв металiв, а також хiмiчних зсувiв протонiв протонованого бетаїну зроблено висновок щодо кислотно-основного характеру взаемодiї iонiв Mg²⁺ i La³⁺ з молекулою барвника. Отриманi данi дозволяють зробити висновок про неприпустимiсть застосування кислотно-основних сенсорiв на основi бетаїнiв у присутностi багатозарядних iонiв металiв.Ассоциация ионов Mg²⁺ и La³⁺ с бетаиновым красителем райхардта в дейтерированном DMSO изучена с использованием метода ПМР. На основании значений химических сдвигов протонов бетаина в присутствии ионов металлов, а также химических сдвигов протонов протонированного бетаина сделан вывод о кислотно-основном характере взаимодействия ионов Mg²⁺ и La³⁺ с молекулой красителя. Полученные данные позволяют сделать вывод о недопустимости применения кислотно-основных сенсоров на основе бетаинов в присутствии многозарядных ионов металлов

Temperature sensitivity of Nd³⁺, Yb³⁺:YF<inf>3</inf> ratiometric luminescent thermometers at different Yb³⁺ concentration

Nd3+ (0.5 mol.%), Yb3+ (1.0, 2.0, 3.0, 4.0, and 8.0 mol.%):YF3 phosphors were synthesized using a co-precipitation method with subsequent hydrothermal treatment and annealing in vacuum. The Nd3+, Yb3+:YF3 phosphors are orthorhombic phase nano-crystals. Luminescence intensity ratio (LIR) of Nd3+ (4F3/2 – 4I9/2, ~866 nm) and Yb3+ (2F5/2 – 2F7/2, ~980 nm) emissions was chosen as temperature-dependent parameter. The energy exchange between 4F3/2 (Nd3+) and 2F5/2 (Yb3+) is phonon-assisted which explains the temperature dependence of LIR. There are Nd3+ to Yb3+ energy transfer (ET), Yb3+ to Nd3+ back energy transfer (BET) and energy diffusion (ED) between Yb3+ ions. The probability of BET decreases with the increase of Yb3+ concentration which leads to LIR dependence on Yb3+ concentration. The maximum absolute temperature sensitivity (Sa) was achieved for Nd3+ (0.5%), Yb3+ (1.0%):YF3 (Sa = 0.0018 K−1 at 148 K). The studied samples demonstrate high stability after 8 cooling-heating cycles. The Nd3+ (0.5%), Yb3+ (1.0%):YF3 phosphors are very promising for temperature sensing

Spectral-Kinetic Properties and Energy Transfer in Nanoparticles of Y<inf>0.5–x</inf>Ce<inf>0.5</inf>Tb<inf> x</inf>F<inf>3</inf> Solid Solution

© 2020, Springer Science+Business Media, LLC, part of Springer Nature. Crystalline nanoparticles of Y0.5–xCe0.5TbxF3, doped with various concentrations (x = 0, 0.005, 0.01, 0.05, 0.1, 0.15, and 0.2) of Tb3+ ions were synthesized by co-precipitation. The crystal structure and chemical composition of nanoparticles were studied using transmission electron microscopy, scanning electron microscopy, and X-ray diffractometry. The obtained nanoparticles of solid solutions had an elliptical shape with a size of 10–15 nm along the long axis and good crystallinity with the structure of a CeF3 crystal. The spectral-kinetic properties of the obtained nanoparticles, and the effect of the concentration of Tb3+ activator ions on the energy transfer from Ce3+ to Tb3+ ions were investigated. Energy transfer from Ce3+ to Tb3+ ions in nanocrystals of the Y0.5–xCe0.5TbxF3 solid solutions occurs mainly through the dipole–dipole interaction. The results of evaluating the efficiency of energy transfer from Ce3+ to Tb3+ ions show its increase with increasing concentration of Tb3+ ions

Characterization of perspective active medium based on mixed crystals Ce3+:LiCaXSr1-XAlF6

© 2020 IEEE. The aim of this work is characterization of perspective active media based on mixed crystals Ce3+:LiCaXSr1XAlF6. Also the optical studies ions in the UV spectral range and effect of the various types of the doping centers on the laser characteristics in the Ce3+:LiCaXSr1-XAlF6 mixed crystals were studied