Luminescence decay kinetics as a tool for quality control of polymer materials used in railway transport

Protective coatings and composite materials based on polymer materials are widely used. They are used in construction, railway, water and air transport to protect various structures from the harmful effects of the environment. In order to create new materials with greater strength and durability, the research related to the development of methods for controlling their quality and the formation processisneeded.The luminescence of chromophores (molecules capable of luminescence) attached to polymer molecules (polymer chains) is an effective tool for this control. The paper discusses the effect of the polymer chain size and the nature of the interaction of its units on the chromophores’ luminescence decay kinetics.

Cadmium-Inspired Self-Polymerization of {LnIIICd2} Units: Structure, Magnetic and Photoluminescent Properties of Novel Trimethylacetate 1D-Polymers (Ln = Sm, Eu, Tb, Dy, Ho, Er, Yb)

A series of heterometallic carboxylate 1D polymers of the general formula [LnIIICd2(piv)7(H2O)2]n·nMeCN (LnIII = Sm (1), Eu (2), Tb (3), Dy (4), Ho (5), Er (6), Yb (7); piv = anion of trimethylacetic acid) was synthesized and structurally characterized. The use of CdII instead of ZnII under similar synthetic conditions resulted in the formation of 1D polymers, in contrast to molecular trinuclear complexes with LnIIIZn2 cores. All complexes 1–7 are isostructural. The luminescent emission and excitation spectra for 2–4 have been studied, the luminescence decay kinetics for 2 and 3 was measured. Magnetic properties of the complexes 3–5 and 7 have been studied; 4 and 7 exhibited the properties of field-induced single-molecule magnets in an applied external magnetic field. Magnetic properties of 4 and 7 were modelled using results of SA-CASSCF/SO-RASSI calculations and SINGLE_ANISO procedure. Based on the analysis of the magnetization relaxation and the results of ab initio calculations, it was found that relaxation in 4 predominantly occurred by the sum of the Raman and QTM mechanisms, and by the sum of the direct and Raman mechanisms in the case of 7.

Роль модельных представлений в описании кинетики люминесценции гибридных нитевидных нанокристаллов

On the example of InP/InAsP/InP nanowires, the role of theoretical models in the photodynamics study of hybrid semiconductor structures is considered. The photodynamics of luminescence of an array of InP/InAsP/InP nanowires formed by molecular beam epitaxy on a Si (III) substrate was studied. Based on a comparison of several kinetic models, including the use of poly-exponential and stretched-exponential functions, the analysis of experimental data is carried out. Experiments were performed by excitation with laser radiation of 633 nm at room temperature. It has been shown that the luminescence decay kinetics of the InAsP nanoinsert is best described in terms of the contact quenching model. The total decay time of the excited state (radiation lifetime) of the InAsP insert was estimated at τ ~ 40 ns. The reasons for the unusually long duration of transfer of excitation from InP have been suggested.

Wavelength dependent luminescence decay kinetics in ‘quantum-confined’ g-C3N4 nanosheets exhibiting high photocatalytic efficiency upon plasmonic coupling

Exciton recombination and its decay kinetics study revealing the nature of co-catalytic contributions in plasmonically active, highly photoactive Au-/g-C3N4 nanosheets.

Спектроскопические свойства KPb-=SUB=-2-=/SUB=-Cl-=SUB=-5-=/SUB=- и RbPb-=SUB=-2-=/SUB=-Br-=SUB=-5-=/SUB=-, легированных Er-=SUP=-3+-=/SUP=- и Yb-=SUP=-3+-=/SUP=-

Er3+ doped lead-halide crystals perform a number of properties which make them perspective for practical use in waveguides and spectrum converters. In current work we have studied luminescence spectra dependencies over the excitation wavelength, luminescence intensity dependences over temperature for up-conversion excitation of most significant lines (530, 550 and 650 nm) under 980 nm excitation. Luminescence decay kinetics under 313 nm and 365 nm excitation in KPb2Cl5:Er3+, RbPb2Br5:Er3+ и KPb2Cl5:Er3++Yb3+ have been measured and theoretical estimates of the lifetimes were made in accordance with Judd-Ofelt technique. Received results can be used in laser systems design and for accuracy evaluation when Judd-Ofelt technique for these crystals is applied.

Люминесцентные свойства боросиликатного стекла, легированного церием

ABS – BGP (Al2O3 – B2O3 – SiO2 – BaCO3 – Gd2O43 – P2O5) glasses doped with different Ce3+ concentrations were prepared by glass melting method. Optical, structural and luminescent properties have been characterized. Emission in the spectral range of 350–550 nm, associated with radiation transitions of Ce3+ ions was recorded. The luminescence decay kinetics is characterized by two components. The fast component is 45–90 ns. For the slow component, a decrease in the decay time from 4 to 0.9 us with increasing cerium ion concentration is shown. Based on the luminescence spectra, an assumption about the existence of various emitting states of the Ce3 + ion in borosilicate glass was made.

Влияние температуры на люминесцентные свойства керамики MgAl-=SUB=-2-=/SUB=-O-=SUB=-4-=/SUB=- : Dy, синтезированной методом искрового плазменного спекания

MgAl2O4:Dy3+ transparent ceramics were synthesized by Spark Plasma Sintering technique. The optical properties, photo- and cathodoluminescence, and luminescence decay kinetics were studied. The effect of temperature on the spectral and kinetic characteristics of luminescence was investigated. There are several emission bands in emission spectra responsible for Dy3+ ions at 458 (4I15/2 - 5H15/2), 480 nm (4F9/2 - 6H15/2), 573 nm (4F9/2 - 6H13/2), 665 nm (4F9/2 - 6H11/2), 750 nm (4F9/2 - 6H9/2), chromium Cr3+ (2Eg - 4A2g), and internal defects such as F+ centers (460 nm) were observed. The temperature quenching of the luminescence in the visible spectral range is observed when the temperature varies from 100 to 300 K. It is shown that in the MgAl2O4: Dy ceramics, the quenching patterns for impurity and intrinsic centers differ. The mechanisms of temperature quenching are discussed.