The anomalous luminescence thermal quenching performance caused by negative thermal expansion has attracted much attention due to the potential application in optical fields. However, the ...downshifting emissions with abnormal thermal quenching achieved by isotropic negative thermal expansion for optical temperature sensing applications are still lacking. Herein, a large enhancement of red emission and a high temperature sensing performance are realized by isotropic negative thermal expansion in ScF3:Tb3+/Eu3+ phosphors ceramics. Specially, a selectively thermal enhanced red emission of Eu3+ from 5D0→7F2 with hypersensitive transition characteristics could be obtained due to the thermal stimulated lattice distortion. Attributing to the shortening of cation spacing, the energy transfer efficiency between Tb3+ and Eu3+ is largely enhanced with the increasing of the temperature from 303 to 473 K. The enhanced energy transfer leads to that the emission of Tb3+ firstly increases and then slightly decreases, whereas the emission from Eu3+ has been largely improved. Finally, an optical temperature sensing strategy based on the fluorescence intensity ratio of the sensitizer Tb3+ (signal ions) and the activator Eu3+ (referring ions) is designed, attributing to the distinguishable luminescence response to the temperature. The obtained maximum relative sensitivity is 1.04 % K−1 (@303 K). Besides, the sensing strategy based on lifetime mode also suggests a maximum relative sensitivity of 1.00 % K−1 at 343 K. It provides a feasible strategy to obtain an optical temperature sensing material with high emission efficiency at a high temperature, which sheds light on the design of luminescence materials keeping high luminescence stability in a wide temperature range in the fields of optical temperature sensing.
A potent luminescent sensor for the detection of iodide ions was developed based on a terbium(
iii
)-based lanthanide-organic framework Tb(cpia)(H
2
O)
2
n
·
n
H
2
O (
1
), which was prepared under ...hydrothermal conditions using the 5-(4-carboxyphenoxy)isophthalic acid (H
3
cpia) bridging ligand. Compound
1
exhibits superior luminescence quenching behavior towards I
−
with high sensitivity and selectivity among various anions and shows real-time response. Moreover, the mechanism of the selective luminescence quenching response for I
−
can be mainly explained by the absorption competition between
1
and I
−
. According to this quenching mechanism, we find that compound
1
can also detect Br
−
by adjusting the excitation wavelength. Significantly, this work could serve as a general guidance for the design and synthesis of pollutant sensors.
A reversible terbium-based luminescent MOF sensor for the detection of I
−
/Br
−
in aqueous solutions with high selectivity and sensitivity.
Abstract
We study satellite counts and quenched fractions for satellites of Milky Way analogs in
Romulus25
, a large-volume cosmological hydrodynamic simulation. Depending on the definition of a ...Milky Way analog, we have between 66 and 97 Milky Way analogs in
Romulus25
, a 25 Mpc per-side uniform volume simulation. We use these analogs to quantify the effect of environment and host properties on satellite populations. We find that the number of satellites hosted by a Milky Way analog increases predominantly with host stellar mass, while environment, as measured by the distance to a Milky Way–mass or larger halo, may have a notable impact in high isolation. Similarly, we find that the satellite quenched fraction for our analogs also increases with host stellar mass, and potentially in higher-density environments. These results are robust for analogs within 3 Mpc of another Milky Way–mass or larger halo, the environmental parameter space where the bulk of our sample resides. We place these results in the context of observations through comparisons to the Exploration of Local VolumE Satellites and Satellites Around Galactic Analogs surveys. Our results are robust to changes in Milky Way analog selection criteria, including those that mimic observations. Finally, as our samples naturally include Milky Way–Andromeda pairs, we examine quenched fractions in pairs versus isolated systems. We find potential evidence, though not conclusive, that pairs, defined as being within 1 Mpc of another Milky Way–mass or larger halo, may have higher satellite quenched fractions.
Effective value of the weak axial-vector coupling strength, g A , in nuclear β and ββ (double beta) decays is discussed. Both Gamow-Teller and first-forbidden β decays are included in the analyses. ...Quenching of g A in β and two-neutrino ββ decays is reviewed and impact of this quenching on neutrinoless ββ decays is addressed. New measurements of β spectra of first-forbidden non-unique β decays are encouraged, to learn about the mesonic enhancement of the weak axial charge in these decays.
In this report we study the dynamics of passive quenching in a single-photon avalanche diode. Our discussion is based on a microscopic description of the electron–hole avalanche coupled to the ...equivalent circuit of the device, consisting of the quench resistor and the junction capacitance. Analytic expressions for the resulting signal shape are derived from this model for simple electric field configurations, and efficient numerical prescriptions are given for realistic device geometries. Space charge effects arising from the avalanche are included using simulations. They are shown to distort the signal shape, but alter neither its basic characteristics nor the underlying quenching mechanism.
Materials with ultralong phosphorescence have wide-ranging application prospects in biological imaging, light-emitting devices, and anti-counterfeiting. Usually, molecular phosphorescence is ...significantly quenched with increasing temperature, rendering it difficult to achieve high-efficiency and ultralong room temperature phosphorescence. Herein, we spearhead this challenging effort to design thermal-quenching resistant phosphorescent materials based on an effective intermediate energy buffer and energy transfer route. Co-crystallized assembly of zero-dimensional metal halide organic-inorganic hybrids enables ultralong room temperature phosphorescence of (Ph
P)
Cd
Br
that maintains luminescent stability across a wide temperature range from 100 to 320 K (ΔT = 220 °C) with the room temperature phosphorescence quantum yield of 62.79% and lifetime of 37.85 ms, which exceeds those of other state-of-the-art systems. Therefore, this work not only describes a design for thermal-quenching-resistant luminescent materials with high efficiency, but also demonstrates an effective way to obtain intelligent systems with long-lasting room temperature phosphorescence for optical storage and logic compilation applications.
This paper concerns the approximation and numerical solution of a singular fractional reaction–diffusion problem. A Riemann–Liouville space-fractional derivative oriented Laplacian is incorporated. ...While our spatial discretization is fulfilled though combined standard and shifted Grünwald formulas, temporal integration is accomplished via an implicit adaptive Crank–Nicolson scheme. It is proven that under proper constraints of the spatial and temporal discretization parameters, the numerical procedure implemented is positive, monotone and numerically stable. Simulation experiments are given to validate correlations between the fractional derivative and critical values including critical lengths, quenching times and locations.
Two porous complexes, namely, {H2N(Me)22Zn5(L)2(OH)2·3DMF·4H2O}n (1), and {H2N(Me)24Cu3(L)2(H2O)2·4DMF·3H2O}n (2) were solvothermally constructed based on a symmetrical V-shaped rigid multicarboxylic ...acid ligand H5L (H5L = 3,5-di(2′,5′-dicarboxylphenyl)benzoic acid). Complexes 1 and 2 display 3D frameworks with various metal clusters. Complex 1 is a 3D porous framework with a (4,8)-connected topology featuring a 1D pore structure in the a-axis direction with a penta-nuclear cluster Zn5(μ2-COO)6(μ1-COO)4(μ3-O)2. By contrast, 2 displays a 3D (3,4)-connected net based on binuclear Cu2(COO)4 paddlewheel SBUs. Complex 1 reveals solid-state luminescent properties at ambient temperature, and the maximum emission peak was observed at ∼443 nm (λex = 339 nm). Meanwhile, 1 shows high selectivity and sensitivity not only for Fe3+ cations but also for Cr2O72− anions via the luminescence quenching effect with a low detection limit, which thus could be a potential crystalline material for detecting these substances. The mechanisms of the quenching effect and sensing properties of 1 were discussed in detail.
We report mechanistic insights into an iridium/nickel photocatalytic C–O cross-coupling reaction from time-resolved spectroscopic studies. Using transient absorption spectroscopy, energy transfer ...from an iridium photocatalyst to a catalytically relevant Ni(II)(aryl) acetate acceptor was observed. Concentration-dependent lifetime measurements suggest the mechanism of the subsequent reductive elimination is a unimolecular process occurring on the long-lived excited state of the Ni(II) complex. We envision that our study of the productive energy-transfer-mediated pathway would encourage the development of new excited-state reactivities in the field of metallaphotocatalysis that are enabled by light harvesting.
The solubility/degradability of bioactive glasses play crucial role in bone tissue engineering applications owing to the release of ions from their structure, which exert therapeutic effects on ...tissues. The present study evaluates the findings of a detailed investigation on the main features and solubility behaviors of newly formulated Nb incorporated glasses (Nb-BGs). New glass formulation in SiO2–CaO–Na2O–P2O5–CaF2–SrO–xNb2O5 (x: 0.0, 0.5, 1.0, and 1.5 mol. %) system was successfully synthesized by melt-quenching technique. Glass composition was verified with Energy Dispersive X-ray Fluorescence spectrometer analysis and its amorphous nature, functional groups of the matrix and morphological features were identified via X-Ray diffraction analyses, Fourier Transform Infrared Spectroscopy and Scanning Electron Microscope analysis, respectively. Network connectivity (NC) of the Nb-BGs was assessed with respect to the role of Nb2O5 in the glass matrix as network former, modifier, or both. In order to evaluate the in vitro solubility of Nb-BGs, released concentrations of particular ions from the glass compositions were determined at certain time points and comprehensively discussed with several mathematical models such as zero-order, first-order, second-order, Higuchi, and Korsmeyer-Peppas for the first time. Results showed that the incorporation of Nb2O5 (up to 1.5 mol. %) increased the density, oxygen density as well as NC values of newly formulated glasses. Si, Na and Ca ions which play a main role in well-defined Hench's mechanism followed mostly second-order release kinetics for all glasses in the mathematical models studied. When the Nb content increase (to 1.5 mol. %) in glass composition, the release mechanism of Si ion according to Korsmeyer-Peppas model shifts from the diffusion mechanism to an erosion-dominant release mechanism.
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