Here, we are reporting a halide precursors acid precipitation method to synthesize Cs2AgIn1–xBixCl6 (x = 0, 0.02, 0.04, 0.08, 0.16, 0.32, 0.64, and 1) microcrystals. Cs2AgInCl6 and Bi derivative double...
First analysis of strong directional surface plasmon-coupled emission (SPCE) of ground-state formed intermolecular aggregates of Rhodamine 110 (R110) in silica nanofilms deposited on silver nanolayers is reported. Until now, the processes of energy transport and its trapping due to aggregate formation have not been studied in the presence of SPCE. A new approach to multicomponent systems with weakly and strongly fluorescent centers making use of fluorophore-surface plasmon interaction is presented. The analysis is based on comparison of experimental free-space emission spectra (F-SE), experimental SPCE with theoretical surface plasmon resonance spectra (SPR). It is shown that, due to the dispersion of SPCE, the detection of weak aggregate emission is straightforward if only the monomers and aggregates fluorescence spectra are somewhat spectrally shifted. SPCE studies confirmed the formation of weakly fluorescent higher order aggregates of R110 in silica films. The results indicate that the increase of energy transfer from monomers to aggregates is due to fluorophore-plasmon interaction.
High-pressure and time-resolved studies of the optical emission from n-type doped GaN/AlN multi-quantum-wells (MQWs) with various well thicknesses are analysed in comparison with ab initio calculations of the electronic (band structure, density of states) and optical (emission energies and their pressure derivatives, oscillator strength) properties. The optical properties of GaN/AlN MQWs are strongly affected by quantum confinement and polarization-induced electric fields. Thus, the photoluminescence (PL) peak energy decreases by over 1 eV with quantum well (QW) thicknesses increasing from 1 to 6 nm. Furthermore, the respective PL decay times increased from about 1 ns up to 10 μs, due to the strong built-in electric field. It was also shown that the band gap pressure coefficients are significantly reduced in MQWs as compared to bulk AlN and GaN crystals. Such coefficients are strongly dependent on the geometric factors such as the thickness of the wells and barriers. The transition energies, their oscillator strength, and pressure dependence are modeled for tetragonally strained structures of the same geometry using a full tensorial representation of the strain in the MQWs under external pressure. These MQWs were simulated directly using density functional theory calculations, taking into account two different systems: the semi-insulating QWs and the n-doped QWs with the same charge density as in the experimental samples. Such an approach allowed an assessment of the impact of n-type doping on optical properties of GaN/AlN MQWs. We find a good agreement between these two approaches and between theory and experimental results. We can therefore confirm that the nonlinear effects induced by the tetragonal strain related to the lattice mismatch between the substrates and the polar MQWs are responsible for the drastic decrease of the pressure coefficients observed experimentally.
The first observation of strong directional surface-plasmon-coupled emission (SPCE) of Rhodamine 110 in silica nanofilms deposited on silver nanolayers is reported. The preparation of the material is described in detail. The intensity of SPCE exceeds 10 times that of free space fluorescence and total linear light polarization in the SPCE ring is observed. A new experimental setup and an original data collection method is presented. Our material completely preserves its fluorescence properties for at least eight months.
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