The temperature dependences of the peak position and width of the photoluminescence band in Al0.1In0.01Ga0.89N layers were explained by Monte Carlo simulation of exciton localization and hopping. The introduction of a doubled-scaled potential profile due to inhomogeneous distribution of indium allowed obtaining a good quantitative fit of the experimental data. Hopping of excitons was assumed to occur through localized states distributed on a 16 meV energy scale within the In-rich clusters with the average energy in these clusters dispersed on a larger (42 meV) scale.

We report on quaternary AlInGaN/InGaN multiple quantum well (MQW) light emitting diode structures grown on sapphire substrates. The structures demonstrate high quality of the p–n junctions with quaternary MQW. At low forward bias (below 2 V), the temperature dependent of current–voltage characteristics are exponential with the ideality factor of 2.28, which is in a good agreement with the model of the injected carrier recombination in the space charge region. This ideality factor value is approximately three times lower than for conventional GaN/InGaN light emitting diodes (LEDs). The obtained data indicate the recombination in p–n junction space charge region to be responsible for a current transport in LED structures with quaternary quantum wells. This is in contrast to InGaN based LEDs, where carrier tunneling dominates either because of high doping of the active layer or due to the high density of localized states.

Lanthanide MOFs with fluorescent sensing and selective adsorption have been synthesized and characterized based on a novel flexible ligand.

We designed a cluster surface smoothing method that can fast locate the minimum of the funnels in the potential energy surface (PES). By inserting the cluster surface smoothing approach into the gradient-based local optimization (LO)-phase and the global optimization (GO)-phase as a second LO-phase, the GO-phase can focus on the global information oWalesf the PES over the various funnels. Following the definition of "basin-hopping" method [D. J. and J. P. K. Doye, J. Phys. Chem. A 101, 5111 (1997)], this method is named as "funnel hopping." Taking a simple version of the genetic algorithm as the GO-phase, the funnel-hopping method can locate all the known putative global minima of the Lennard-Jones clusters and the extremely short-ranged Morse clusters up to cluster size N=160 with much lower costs compared to the basin-hopping methods. Moreover the funnel-hopping method can locate the minimum of various funnels in the PES in one calculation.

An open terbium-organic framework (UPC-11) based on a rigid tetracarboxylate ligand was successfully assembled, which exhibits excellent solvent-dependent photoluminescence (PL). Moreover, UPC-11 displays rapid and selective sensing of nitroaromatic compounds (NACs), especially for 4-nitrophenol (4-NP), which represents the first Tb MOF that can be used as fluorescence detection of 4-NP. N itroaromatic compounds (NACs) have become serious pollution sources of groundwater, soils, and other security applications due to their explosivity and high toxicity. 1,2 Hence, the convenient and high-efficiency detective technologies based on the NACs have received much attention from chemists. Although some traditional detective methods bear high selectivity such as metal detectors, gas chromatography, surface-enhanced Raman spectroscopy, electron capture detection, and cyclic voltammetry, 3−6 they are usually expensive, inconvenient, and not very good for manipulation. Therefore, new technologies need to be developed so that we may cheaply and rapidly complete detection. The fluorescencebased sensing materials have recently been considered as one of the most excellent and promising techniques in the detection of NACs, 7−9 because this kind of technique possesses several advantages such as high selectivity, simplicity, portability, and the ability to be applied in both solution and solid phases. 10−13 In the past decade, some oligomeric, polymeric, or nanoscale fluorescent materials have been prepared and used in the detection of NACs. 14−16 However, it is still a great challenge for chemists to develop novel fluorescent materials for the detection of NACs because it is not facile to introduce chromophores into the above-mentioned materials as fluorescence sensor.Metal−organic frameworks are a new class of crystalline materials, which are built from metal cations or clusters and organic ligands. 17−19 The fluorescent behavior of an MOF is highly dependent on the organic ligands and metal ion/cluster; thus, it is facile to construct fluorescent MOFs by using either organic ligands with chromophores or metal ions such as Zn 2+ , Cd 2+ , or Ln 3+ , or utilizing the combination of these two parts. 20−23 Li et al. pioneered the application of fluorescent MOFs on the detection of NACs. In 2009, they first reported a Zn MOF exhibiting fast and reversible detection of high explosives based on mixed ligands. 24 Following that, a series of fluorescent MOFs containing Zn 2+ and Cd 2+ ions were documented for the rapid fluorescence detection of NACs. 25−29 For example, Su et al. reported a two-dimensional Cd MOF that can recognize NACs with different numbers of nitro groups. 30 Moon et al. directly observed the interaction sites between NACs and the framework by a luminescent Libased MOF. 31 Surprisingly, fluorescence detection of NACs based on Ln MOFs was seldom explored, although Ln MOFs show characteristic emission properties and have been considered a class of popular luminescent materials that possess potential applications in bio...