Phonon-phonon and electron/exciton-phonon coupling play a vitally important role in thermal, electronic, as well optical properties of metal halide perovskites. In this work, we evaluate phonon anharmonicity between electronic vibrational excitations novel double perovskite Cs2NaFeCl6 single crystals. By employing comprehensive Raman measurements combined with first-principles theoretical calculations, identify four Raman-active modes. Polarization these modes imply Fm3̅m symmetry the...

Improvement of polyvinyl alcohol stability against ultraviolet (UV) illumination is achieved by introducing cadmium sulfide (CdS) nanoparticles into the polymeric matrix. Enhancement analyzed optical characterization methods. UV protection diminishing probability photo-activated formation defects in polymer. The sources polymer are lowering efficiency excitation via partial absorption incident light embedded as well de-excitation macromolecules that have already absorbed quanta energy drain...

Based on the results of temperature-dependent photoluminescence (PL) and absorption measurements, PL emission in GaNP epilayers GaNP/GaP multiple quantum well structures with N composition up to 4% is shown be dominated by optical transitions within deep states likely related clusters. With increasing composition, these are become resonant conduction band alloy thus optically inactive, leading apparent redshift maximum position.

The absorption edge of GaNxP1−x alloys (0.01⩽x⩽0.03) is shown to exhibit a direct-band gap-like behavior. Thermal variation the band gap energy Eg, however, found be same or even smaller than that for indirect GaP and depends on N content. effect tentatively attributed following counteracting contributions formation. An interaction with N-related localized states, especially significant in vicinity crossover (e.g., x=0.013), causes substantial slow down Eg shift temperature. On contrary, an...

Exciton spin relaxation in diluted magnetic semiconductor (DMS) structures based on ZnMnSe is closely examined as a function of exciton splitting an external field. A drastic increase observed when exceeds the longitudinal optical (LO) phonon energy. Direct experimental evidence has been provided from (1) injection DMS to adjacent nonmagnetic quantum well that can be modulated by LO-assisted and (2) hot photoluminescence within where flip accompanied emission one LO phonon.

This work describes fabrication and characterization of two types surface‐enhanced Raman scattering (SERS) substrates based on starlike gold nanoparticles (NPs). Type I SERS are formed by adsorption from chemically synthesized colloidal solution onto the modified glass substrates. II fabricated direct nucleation growth Au NPs immersed in precursors solution. Morphology, optical, characteristics both studied. Study shows that varying diameters nanostars cores lengths their spikes during...

The ability of attaining desired spin functionality by adjusting structural design is demonstrated in diluted magnetic semiconductor (DMS) quantum structures based on II–VI semiconductors. following enabling functions are achieved tuning the ratio between rates exciton relaxation within DMS and escape from it to an adjacent nonmagnetic detector. Spin switching realized when using a thin layer Zn0.95Mn0.05Se as manipulator attributed fast preceding relaxation. alignment accomplished tunneling...

CdS nanoparticles have been synthesized in aqueous solution using polyvinyl alcohol (PVA) as a capping reagent. The effects of exposure by ultraviolet (UV) light on optical properties nanocomposites consisting colloidal and polymer PVA matrix were studied employing photoluminescence (PL) spectroscopy. It is shown that UV-induced changes the intensity are caused creation healing non-radiative recombination centers. also concluded nanocomposites, PL predominantly governed processes at NP/PVA interface.

A series of solid nanocomposites containing CdS nanoparticles in polymeric matrix with varied conditions on the interface particle/polymer was fabricated and studied by photoluminescence (PL) optically detected magnetic resonance (ODMR) methods. The results revealed interface-related features both PL ODMR spectra. paramagnetic centers are concluded to be involved processes photo-excited carriers relaxation.

Abstract In this study we employ a new method for growth of carbon‐doped wurtzite crystalline GaN (GaN:C) based on vapour phase transport Ga by the pseudohalide hydrogen cyanide HCN. GaN:C layers with thicknesses from 10 to 100 μm and up 19 mm in size were grown gallium melt ammonia as feeding materials carbon‐containing equipment. The properties characterized low‐temperature photoluminescence (LTPL), High‐Resolution X‐ray Diffraction (HRXRD), Secondary Ion Mass Spectrometry (SIMS)...

Abstract White‐light emitting porous SiO 2 :C layers on silicon wafers have been fabricated by oxidation of carbonized silicon. The study was focused mainly the identification mechanism light emission and photo‐induced degradation. effect carbonization temperature exposure to intense ultraviolet irradiation photoluminescence (PL) properties studied steady state time‐resolved PL measurements. Two types degradation phenomena were observed: reversible irreversible. irreversible is suggested be...

Abstract The vibrational spectra of a molecule and related molecular crystal are systematically analyzed theoretically with the account influence anharmonic interactions between vibrations. specific anharmonism‐induced features in revealed, spectral lineshapes at varied strength interaction simulated. proposed general theoretical approach is used for fitting experimental CO 2 substance gas phases. Pretty good coincidence data results demonstrated, constants obtained. can be to interpret...

Changes in the photoluminescence (PL), microstructural morphology and chemical nature of surface porous silicon (PS) when it is attacked with a 1:1 mixture concentrated hydrofluoric acid water have been studied. As PS dissolves, structure essentially destroyed while appearance composition change. At same time, intensity peak wavelength PL change dramatically. The simultaneous investigation PL, FTIR absorption SEM observation layers (PSL) lend support to view that passivation, particular by...

The carbonized silica (SiO 2 :C) nanopowders were prepared by chemical modification of fumed (aerosil) phenyltrimethoxysilane followed thermal annealing at temperature in range 500-800 °C nitrogen flow. Their magnetic properties investigated electron paramagnetic resonance (EPR) the from 4.2 K to 292 K. initial and annealed SiO :C samples revealed carbon (C) related defects. radicals (CRR) with g -factors 2.0042, 2.0039 attributed oxygen (O)-centered CRR C-centered a nearby O heteroatom,...

GaAsBi nanowires represent a novel and promising material platform for future nano-photonics. However, the growth of high-quality alloy is still challenge due to large miscibility gap between GaAs GaBi. In this work we investigate effects Bi incorporation on lattice dynamics carrier recombination processes in GaAs/GaAsBi core/shell grown by molecular-beam epitaxy. By employing photoluminescence (PL), PL excitation, Raman scattering spectroscopies complemented scanning electron microscopy,...

cw hot photoluminescence (PL) complemented by transient PL measurements is employed to evaluate momentum and spin relaxation of heavy hole (HH) excitons in $\mathrm{Zn}\mathrm{Mn}\mathrm{Se}∕\mathrm{Cd}\mathrm{Se}$ superlattices. The rate acoustic-phonon assisted concluded be comparable the total exciton decay processes, about $(2--3)\ifmmode\times\else\texttimes\fi{}{10}^{10}\phantom{\rule{0.3em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1}$, independent applied magnetic fields. In fields when...

Abstract The effects of pH value and precursors concentrations in the growth solution as well ultrasound irradiation on properties CdS:Mn nanoparticles PVA matrix are studied. Analysis photoluminescence spectra indicates that increase leads to density surface electron states participate radiative transitions enlargement nanoparticles. We discuss a stabilization sizes at pH=6 change nanoparticle size with decreasing elevated ions HS ‐ . It is shown ultrasound‐treated samples particles does...

The conditions for growing CdS nanoparticles suitable the visualization of biological tissues were theoretically studied and experimentally checked. optimal ranges pH values precursors' concentrations determined. applicability mercaptoethanol-capped in vitro luminescence several cellular forms histological specimens human placenta has been proven.

Fumed silica with a specific area of 295 m2/g was carbonized by successive phenyltrimethoxysilane treatments followed annealing in inert atmosphere up to 650 °C. Emission, excitation, kinetics, and photo-induced bleaching effects were investigated steady state time-resolved photoluminescence spectroscopies. The local chemistry also studied infrared transmission spectroscopy. Strong ultraviolet visible observed the samples after chemical treatments/modifications thermal annealing. It has been...