Decrease In Emission Intensity Research Articles

Enhancement of photo luminescent and magnetic properties of surface modified zinc sulphide nanoparticles by manganese doping

In the current paper we have reported the structural, optical and magnetic properties of manganese doped (1% to 10%) zinc sulphide nanoparticles synthesised by simple chemical co-precipitation method at room temperature. The crystal structure of the synthesised nanoparticles has been confirmed by X-ray diffraction and the average crystallite size calculated by Scherrer formula was about 3.0 nm. A slight quenching in the crystallite size with the doping was also observed. The FESEM images showed spherical shape particles with uniform size distribution. The elemental composition of pure and manganese doped zinc sulphide was confirmed by EDAX attached to FESEM. The UV-Vis spectra has an absorption edge at 321 nm with sharp fall in the absorption confirming the particles of uniform size distribution with no shift in the absorption edge with the doping. The band gap widening was observed (4.4 eV) and the particle size (3.4 nm) calculated was by effective mass approximation. The photoluminescence spectra has wide emission spectra with the peaks at 397 nm, 414 nm and 487 nm with increase in the intensity with the doping concentration giving a peak at 1% of doping and decrease in emission intensity after that. The hysteresis curve shows the ferromagnetism and the saturation magnetisation increases with the doping concentration.

Impacts of urbanization on carbon emissions: An empirical analysis from OECD countries

The impacts of urbanization on carbon emissions have attracted widespread attention for a long time. Quantitative research on the impacts is of great significance for formulating carbon reduction policy. Based on the dynamic panel autoregressive distribution lag (ARDL) model, we systematically study the general and heterogeneous long-run equilibrium relationships, short-run dynamic relationships, impact mechanism and lag effect between urbanization and three carbon emission dimensions in OECD high-income countries during long period. The main empirical results indicate that developed countries tend to have the same negative impacts of urbanization on carbon emissions, although there are differences in the endowments of different countries. The impact is relatively weak, for each percentage point increase in urbanization rate, CO 2 emissions per capita decrease by 0.015%, total CO 2 emissions decrease by 0.012%, and CO 2 emission intensity decrease by 0.009%. All member countries have achieved the decoupling of urbanization and carbon emissions. Urbanization affects carbon emissions by affecting economic growth, energy efficiency, and final energy consumption structure. This paper further reveals the multi-level impacts of urbanization on carbon emissions and provides policy implications of achieving carbon reduction through urbanization's agglomeration effect for government decision makers. • Estimate the impact of urbanization on carbon emissions based on panel ARDL model. • Analyze general & heterogeneous long-, short-run relationship and impact mechanism. • Urbanization decreases carbon emissions but the impact is weak in OECD countries. • Developed economies have achieved the decoupling of urbanization and CO 2 emissions. • Promote urbanization process and exert its scale effect to reduce carbon emissions.

Tris(5‐aryl‐1,3,4‐oxadiazolyl)benzotrithiophenes – Discotic Liquid Crystals with Enormous Mesophase Ranges

AbstractC3‐symmetrical, alkoxyphenyl substituted 2,5,8‐(tris‐1,3,4‐oxadiazol‐2‐yl)benzo [1,2‐b; 3,4‐b′; 5,6‐b′′]trithiophenes (OXD‐BTT) are synthesized via threefold Huisgen‐reaction. A broad variation of alkoxy substitution pattern and chain lengths is reported. The thermal behavior was investigated via differential scanning calorimetry (DSC), polarized optical microscopy (POM) and thermogravimetry (TGA). Optical properties were studied via UV‐Vis and fluorescence spectroscopy. Structural information of the LC phases was gained from X‐ray diffraction on oriented fibers. OXD‐BTT provide enormous phase widths (ΔT≥289 K) with clearing points close to thermal decomposition. Most of the derivatives exhibit two different mesophases, the lower phase with a rectangular 3D‐structure and a hexagonal 2D‐lattice at higher temperature. The variation of the chain length allows a tuning of melting and clearing points. OXD‐BTT emit blue light with fluorescence quantum yields up to 30 % in good solvents. The emission is very sensitive to aggregation, thus, in poor solvents the emission intensity decreases, and red shift of maxima occurs.

Chinese cities exhibit varying degrees of decoupling of economic growth and CO2 emissions between 2005 and 2015

Summary Cities, contributing more than 75% of global carbon emissions, are at the heart of climate change mitigation. Given cities' heterogeneity, they need specific low-carbon roadmaps instead of one-size-fits-all approaches. Here, we present the most detailed and up-to-date accounts of CO2 emissions for 294 cities in China and examine the extent to which their economic growth was decoupled from emissions. Results show that from 2005 to 2015, only 11% of cities exhibited strong decoupling, whereas 65.6% showed weak decoupling, and 23.4% showed no decoupling. We attribute the economic-emission decoupling in cities to several socioeconomic factors (i.e., structure and size of the economy, emission intensity, and population size) and find that the decline in emission intensity via improvement in production and carbon efficiency (e.g., decarbonizing the energy mix via building a renewable energy system) is the most important one. The experience and status quo of carbon emissions and emission-GDP (gross domestic product) decoupling in Chinese cities may have implications for other developing economies to design low-carbon development pathways.

The red light emission in 2D (C4SH3CH2NH3)2SnI4 and (C4OH7CH2NH3)2SnI4 perovskites.

Two-dimensional (2D) perovskites have a large exciton binding energy due to the structure of the quantum confinement, which produces a faster radiative recombination, and so are promising potential materials for light-emitting diodes. However, most of the highly efficient hybrid halide perovskites are based on the toxic Pb-based materials, so the replacement of Pb with less toxic and suitable substitute elements has been investigated for environmental efficient materials. Herein, we report the Sn-based 2D perovskites, which include (TPM)2SnI4 (TPM = C4SH3CH2NH3) and (TFF)2SnI4 (TFF = C4OH7CH2NH3), as red emission materials. Structural characterization by single crystal X-ray diffraction reveals that (TPM)2SnI4 undergoes a structural evolution from the orthorhombic space group Cmc21 (100 K) to Pbca (298 K), while the (TFF)2SnI4 perovskite exhibits the monoclinic space group P21/c at 100 K and 298 K. The inorganic framework of (TFF)2SnI4 was separated by the bilayer TFF chains with an empty space, which is an effective structure to increase the quantum confinement effect. The band gaps of the (TPM)2SnI4 (1.80 eV) and (TFF)2SnI4 (1.73 eV) compounds indicate the direct band gap semiconductor materials. From the time-resolved photoluminescence results, it can be seen that (TPM)2SnI4 produces uniform short emission (0.73 ns) throughout the entire powder crystals, whereas (TFF)2SnI4 has a uniform and long emission life time (47 ns). Temperature-dependent photoluminescence (PL) studies indicate that the (TPM)2SnI4 and (TFF)2SnI4 perovskites have a strong split red emission at low temperature due to the vibration of the inorganic framework. As the temperature increases, the PL spectra shift to the high energy region and the emission intensity decreases. The PL spectra of (TPM)2SnI4 and (TFF)2SnI4 perovskites have maximum peak wavelengths at 622 nm and 640 nm, and show the photoluminescence quantum yields of 0.30% and 1.71%, respectively.

Optical emission spectroscopy of radio frequency inductively coupled plasma for cold hydrogenation of nanoparticles

The radio frequency inductively coupled plasma (ICP) offers an alternative “cold” way to affect the size, composition, structure, and surface functionality of nanoparticles (NPs), such as metal oxide NPs, providing further adjustment of their physical and chemical properties. The ICP was monitored in-situ by optical emission spectroscopy (OES). In particular, hydrogen, oxygen, argon, and nitrogen plasma was studied. OES data show that despite the decrease of the optical emission intensity with increasing gas pressure, the concentration of atomic hydrogen increases with pressure and radio frequency power.

Dual-Affinity Ratiometric Quenching (DARQ) Assay for the Quantification of Therapeutic Antibodies in CHO-S Cell Culture Fluids.

More than 100 monoclonal antibodies (mAbs) are in industrial and clinical development to treat myriad diseases. Accurate quantification of mAbs in complex media, derived from industrial and patient samples, is vital to determine production efficiency or pharmacokinetic properties. To date, mAb quantification requires time and labor-intensive assays. Herein, we report a novel dual-affinity ratiometric quenching (DARQ) assay, which combines selective biorecognition and quenching of fluorescence signals for rapid and sensitive quantification of therapeutic monoclonal antibodies (mAbs). The reported assay relies on the affinity complexation of the target mAb by the corresponding antigens and Protein L (PrL, which targets the Fab region of the antibody), respectively, labeled with fluorescein and rhodamine. Within the affinity complex, the mAb acts as a scaffold framing the labeled affinity tags (PrL and antigen) in a molecular proximity that results in ratiometric quenching of their fluorescence emission. Notably, the decrease in fluorescence emission intensity is linearly dependent upon mAb concentration in solution. Control experiments conducted with one affinity tag only, two tags labeled with equal fluorophores, or two tags labeled with fluorophores of discrete absorbance and emission bands exhibited significantly reduced effect. The assay was evaluated in noncompetitive (pure mAb) and competitive conditions (mAb in a Chinese Hamster Ovary (CHO) cell culture harvest). The "DARQ" assay is highly reproducible (coefficient of variation ∼0.8-0.7%) and rapid (5 min), and its sensitivity (∼0.2-0.5 ng·mL-1), limit of detection (75-119 ng·mL-1), and dynamic range (300-1600 ng·mL-1) are independent of the presence of CHO host cell proteins.

A multi-responsive pyranone based Schiff base for the selective, sensitive and competent recognition of copper metal ions

Exploring a new multi-responsive pyranone chemosensor capable of sensing copper ions specifically and selectively through colorimetric, UV–Vis absorption and fluorescence methods is of great importance. In this piece of work, a novel pyranone based Schiff base ligand 4-Hydroxy-6-methyl-3-[1-(2-morpholin-4-yl-ethylimino)-ethyl]-pyran-2-one (DM) was synthesized by the condensation of dehydroacetic acid and 4-(2-aminoethyl) morpholine. The structural determination of ligand DM was executed using distinct spectral techniques i.e.,1H NMR, 13C NMR, FT-IR and HR-MS techniques. The reported Schiff base DM showed an immediate colorimetric change from pale yellow to colorless accompanied by a strong change in the UV–Vis absorption band onto the addition of Cu (II) ions. This metal ligand chelation leads a decrease in ICT process. Also the decrease in fluorescence emission intensity of Schiff base DM with Cu (II) ions addition showed its turn-off behavior towards copper ions. Further absorption/ emission titration studies, Job’s plot, HR-MS and 1H NMR titration data designated 2:1 stoichiometric ratio between DM and Cu (II) ions respectively. Density functional theory studies were also performed to authenticate the binding mechanism theoretically. The sensitivity of Schiff base DM towards Cu (II) ions was applicable at every pH conditions and at the same time DM exhibited selectivity towards Cu (II) ions with a negligible interference of other metal ions. DM showed a detection limit of 7.7 nM towards copper ions via fluorescence emission studies. The best part about DM is that it has good stability but showed an instant chemical reversibility when titrated with EDTA solution.

Water-soluble luminescent copper nanoclusters as a fluorescent quenching probe for the detection of rutin and quercetin based on the inner filter effect.

In the present study, we proposed a simple, sensitive and selective fluorescence method for the detection of rutin (Rut) and quercetin (Que) based on the inner filter effect (IFE) utilizing water- soluble cysteine-stabilized copper nanoclusters (Cys-CuNCs) as a fluorescent probe. The Cys-CuNCs were successfully synthesized and characterized using UV-visible absorption, emission, Fourier-transform infrared (FT-IR) spectroscopy, fluorescence lifetime, high resolution transmission electron microscopy (HR-TEM) and zeta potential measurements. Cys-CuNCs exhibited bluish-green luminescence under UV light with characteristic emission maxima at 486 nm. Cys-CuNCs was successfully exploited as fluorescent probes for the detection of Rut/Que. The addition of increasing concentrations of Rut/Que led to a gradual decrease in the emission intensity of Cys-CuNCs. The decrease in Cys-CuNC emission intensities were attributed to the strong IFE and static quenching mechanism. The calculated limit of detection values for Rut and Que were as low as 0.021 μM and 0.035 μM, respectively. The Cys-CuNCs sensing probe exhibited excellent selectivity in the presence of other potential interfering compounds. Furthermore, the present method was successfully applied to the analysis of both Rut and Que in biological samples.

Optical properties of CuO/ZnO composites prepared by mechanical grinding

In this work, ZnO and CuO were first prepared by thermal evaporation and direct precipitation, respectively, and then CuO/ZnO composites were obtained by mechanical grinding the mixtures of CuO and ZnO. Scanning electron microscopy, Raman spectroscopy, Raman imaging, UV–vis absorption spectroscopy, and photoluminescence spectroscopy were used to analyze the morphology, structure, and optical properties of CuO/ZnO composites. Raman spectra suggest that the prepared ZnO has a high crystalline quality, while the CuO/ZnO composites have an internal stress. Compared with ZnO, the absorption edge of CuO/ZnO composites shows a red-shift, and the absorption intensity in the visible region is increased greatly. Pure ZnO shows a strong ultraviolet (UV) emission and a weak green emission. As for the CuO/ZnO composites, with the increase of CuO content, the intensity of the UV emission is gradually reduced and the UV peak is gradually moving towards the longer wavelength direction. The decrease in the UV emission intensity should be attributed to interface effects, and the red-shift of UV emission peaks may be caused by unintentional Cu-doping.

Size distribution and formation processes of aerosol water-soluble organic carbon during winter and summer in urban Beijing

Size-resolved aerosol organic carbon (OC) and water-soluble OC (WSOC) was determined weekly in urban Beijing between 2013 and 2018. The results showed that in winter, the concentrations of WSOC and OC in fine (<2.1 μm) and coarse (>2.1 μm) mode were highest in 2013. During the following years, the concentrations of WSOC and OC were lower but an increasing trend was found from 2014 to 2016, which might be due to the increasing precursor concentrations. From summer 2013 to 2018, the concentrations of OC and WSOC in both fine and coarse mode decreased, which might be affected by decreasing emission intensity and photochemical oxidation. To characterize the seasonality of WSOC, two intensive field observations were further performed in winter 2013 and summer 2018. In winter of 2013, WSOC was mainly enriched in PM1 (<1 μm) on clean days and lightly polluted days. In addition, the fine mode maximum shifted from 0.43-0.65 μm to 1.1–2.1 μm with the haze development due to the hygroscopic growth of particles. In summer of 2018, the WSOC was mainly concentrated in PM1, but in a few samples, the maximum size appeared in coarse mode. This difference might due to the different relative humidity and air mass sources. While the formation process of WSOC in winter was affected by photochemical oxidation below 2.1 μm, in 1.1–2.1 μm, it tended to change from photochemical oxidation to aqueous-phase oxidation. For the coarse mode WSOC formation in winter, however, it was mainly affected by heterogeneous processes. The findings advanced our understanding of the annual trends, size distribution and formation processes of WSOC, with significant implications for air pollution control in Beijing and surrounding regions.

Synthesis of Cit-NaYF4: Yb, Tm@phenolic formaldehyde resin (PFR)@Au composites as an optical sensor for the detection of Cu(Ⅱ) ions

Abstract A facile hydrothermal method was employed to synthesize the core-shell structure up-conversion Cit-NaYF4:Yb, Tm (UC)@phenolic formaldehyde resin (PFR) nanoparticles (NPs). UC NPs can enhance the emission intensity of the PFR shell, which contributes to improving the fluorescence detection sensitivity of UC@PFR NPs. Au NPs were loaded onto the surface of PFR shell in situ through the good reduction of the hydroxyl group in PFR. The emission intensity of UC@PFR decreased greatly in the presence of Au nanoparticles due to fluorescence resonance energy transfer (FRET) mechanism between UC@PFR and Au NPs. However, the mixture of H2O2 and SCN− could prevent the decrease of emission intensity of UC@PFR@Au composites because of the oxidation reaction between H2O2 and Au nanoparticles in the presence of SCN−. Also, Cu2+ can prevent the oxidation reaction to occur, which results in the slight change of emission intensity of UC@PFR@Au in the presence of H2O2 and SCN−. Thus, the as-synthesized UC@PFR@Au particles were used to detect Cu2+ sensitivity. The good linear correlation equation between the fluorescence intensity of UC@PFR@Au particles and the concentration of Cu2+ in the range of 4–90 nM (R2 = 0.99) was established with the low detection limit (LOD) of 0.54 nM. Furthermore, the as-synthesized particles were employed to detect Cu2+ in the actual water sample with satisfying results.

Dispersion and Interaction of Charged Fluorescent Dyes in Protein-Polymer Surfactant-based Non-Aqueous Liquid.

Viscous, non-aqueous liquid comprising stoichiometric conjugates of polymer surfactant-bovine serum albumin (PSpBSA) is used as a host matrix for the dispersion of chemically distinct hydrophilic dyes. Using a combination of bright field polarized optical microscopy and fluorescence spectroscopy, we investigate the dispersion of dry and powdered cationic (Rhodamine 6G; Rh6G) and anionic (Fluorescein; FL) dyes in the PSpBSA liquid at room temperature. As the dyes disperse and dissolve in the PSpBSA liquid, it results in a pronounced increase in emission intensity of the former. Interestingly, a shift from 571 to 582 nm is observed in the emission maxima of Rh6G as it disperses in the PSpBSA solvent. Whilst no such red shift is found for the Rh6G dispersion in the aqueous solutions of either native BSA or polymer-surfactant conjugated BSA, a similar shift occurs when Rh6G is dispersed in neat polymer-surfactant (PS), suggesting the interaction of the dye with the PS chains. In the case of anionic FL, no shift is observed in its emission maximum as it disperses in the PSpBSA liquid. Furthermore, within 120 minutes of FL dispersion in the PSpBSA liquid, we observe a ≈26 % decrease in the tryptophan emission intensity (λexc. =285 nm; λemi. =330 nm) of BSA, which could be attributed to both static and dynamic quenching. Our findings provide a proof of concept of an alternative non-aqueous solvent matrix which can dissolve and disperse charged fluorescent dyes, provide suitable binding sites, and show substantial photoluminescence. Thus, it can be envisaged for utilization as an alternative solvent medium for lasing dyes and related applications.

A modified and improved method to measure economy-wide carbon rebound effects based on the PDA-MMI approach

Although energy technological progress has been regarded as an important driver for reducing carbon emissions, the existence of carbon rebound effect prevents a portion of the potential carbon reductions to be realized. Compared with the energy rebound effect, research on the carbon rebound effect is scarce because it is always equated with the energy rebound effect. However, the carbon rebound effect is more complex. Given that the traditional method for carbon rebound effect assessment only reflects energy rebound effects, our study proposed an improved production-theoretical decomposition analysis (PDA)-Meta-frontier Malmquist index (MMI)-based method and explored carbon rebound effects in China from 2006 to 2015. Our results show that (1) the eastern and western regions faced fewer carbon rebound effect risks compared with those of the central region due to decreasing emission intensity associated with energy technological progress; (2) the reductions in emission intensity in the eastern region relied both on coal and non-coal technology, whereas the western region only relied on coal technology; and (3) the non-coal technology in the eastern region was at the meta-frontier, whereas the non-coal technology of other regions exhibited catch-up effects.

Synthesis and characterization of gold (Au): Fullerene (C60)-Poly (vinyl pyrrolidone) nanofluids in an alcoholic medium

Objectives: To synthesize gold (Au) doped fullerene (C60)-Poly (vinyl pyrrolidone)PVP nanofluids in an alcoholic medium. Methods: A simple chemical reduction method was adopted to synthesize Au nanoparticles and then these NPs were doped into the C60-PVP NFs by ultra-sonication. The samples were characterized using spectrophotometer, rheometer and microscope. Findings:We reported Surface Plasmon Resonance enhanced p !p C60(sp2)electron transition in PVP molecules upon insertion of NG into C60 NFs with PVP in butanol. Electron transfer PVP!Au(NG) causes a drastic decrease in the light emission in PVP moieties in a Au:C60-PVP complex. A noticeable red shift of the C=O stretching band of PVP reveals surface interaction between “>C=O and Au-atom. Rheological study of NFs reveals non-Newtonian behavior with an enhanced yield stress and follows a typical Bingham type flow characteristics.High resolution transmission electron micrograph shows formation of Au-C60 metal-non metal NPs of hexagonal shape. Novelty: Decrease in light emission intensity of PVP molecules in presence of Au NPs hints that it could be a candidate for sensing applications. Keywords: Nanogold; nanofluids; surface plasmon resonance; light emission; rheological properties

Revealing contributions to sulfur dioxide emissions in China: From the dimensions of final demand, driving effect and supply chain

More stringent air pollution control measures implemented during the 12th Five-Year Plan period contributed to some achievements on air quality improvement in China. Considering more focus on production-side emissions, it requires to identify what drove changes in pollutant emissions during this period from demand-side. This study is devoted to revealing the contributions to changes in SO2 emissions during 2010-2015 from three dimensions including final demand, driving effect and supply chain. Based on the harmonized input-output framework and emission datasets, demand-driven accounting, structural decomposition analysis and structural path decomposition analysis are conducted progressively. The results indicate that fixed capital formation and exports were the main drivers of demand-driven emissions during the study period, contributing more than 60% in the total. Changes in emission intensity and per capita final demand were the effects with most prohibiting and promoting impacts on emissions, decreasing 9.98 million tons (Mt) and increasing 5.99 Mt, respectively. The supply chain contributed most to increasing emissions was “Manufacture of nonmetallic mineral products → Construction → fixed capital formation” mainly affected by increased emission intensity; that contributed most to decreasing emissions was “Production and Supply of Power and Heat → urban residential consumption” mainly affected by decreased emission intensity. Some policy implications targeting the three dimensions are discussed accordingly. The quantified contributions and uncovered driving mechanism regarding SO2 emissions may assist in facilitating more complete air pollution control strategies from multiple dimensions in the future.

Multicolour tuning of different RE ion doped CaMoO4 nanoparticles by single wavelength excitation

A novel Li+ co-doped RE doped CaMoO4 nanospheres were synthesized adopting polyol technique under urea hydrolysis method. XRD confirms that all the ensued particles are crystallized in the scheelite type tetragonal phase. Transmission electron microscopy observation confirms the formation of small spherical undoped and 5 at % Eu3+, Sm3+ and Dy3+ doped CaMoO4 NPs with a narrow particle size distribution and an average particles diameter of 10.64, 7.18, 3.77 and 3.62 nm, respectively. An increase in the emission intensity with the incorporation of Li ion in the host lattice was discussed in detail. It was found that Li+ ion act as a charge compensator or sensitizer for decreasing emission intensity ratios of MoO42− group to the activator ions. Our work may provide an alternative pathway for tailoring nanocrystals with enhanced optical properties, paving the way for their utilities in the commercialization in optical display systems, lasers and optoelectronic devices.

Albumin binding study to sodium lactate food additive using spectroscopic and molecular docking approaches

Sodium lactate (SL) is a lactic acid salt that is used in the food and pharmaceutical industries due to its antioxidant and antibacterial properties. Therefore, for the first time we investigated the interaction of SL with the bovine serum albumin (BSA) using spectroscopic and molecular modeling studies under physiological conditions. Fluorescence studies were performed at three different temperatures and the attained results showed emission intensity decrease upon addition of SL. Calculated thermodynamic parameters demonstrated that van der Waals interactions and hydrogen bonds were the main forces in the binding of SL to BSA. The negative sign of standard Gibbs free energy (∆G°) showed that the BSA-SL complex formation was a spontaneous molecular interaction process. The results of UV–Vis spectroscopy showed a ground-state complex formation between BSA and SL and confirmed the results of fluorescence quenching study which showed the quenching mechanism was static. Results of molecular docking indicated a stable binding for lactate to BSA on Sudlow II and lowest calculated binding energy for the interaction was −7.87 kcal/mol. Also, the significant role of two amino acid residues (Lys 499, Lys 533) in the binding process of BSA with SL was approved. This investigation provides important insight into the mechanism of sodium lactate interaction with BSA in vitro.

Superior Stability and Emission Quantum Yield (23% ± 3%) of Single-Layer 2D Tin Perovskite TEA2 SnI4 via Thiocyanate Passivation.

Tin-based perovskite, which exhibits narrower bandgap and comparable photophysical properties to its lead analogs, is one of the most forward-looking lead-free semiconductor materials. However, the poor oxidative stability of tin perovskite hinders the development toward practical application. In this work, the effect of pseudohalide anions on the stability and emission properties of single-layer 2D tin perovskite nanoplates with chemical formula TEA2 SnI4 (TEA = 2-thiophene-ethylammonium) is reported. The results reveal that ammonium thiocyanate (NH4 SCN) is the most effective additive in enhancing the stability and photoluminescence quantum yield of 2D TEA2 SnI4 (23 ± 3%). X-Ray photoelectron spectroscopic investigations on the thiocyanate passivated TEA2 SnI4 nanoplate show less than a 1% increase of Sn4+ signal upon 30 min exposure to air under ambient conditions (298 K, humidity ≈70%). Furthermore, no noticeable decrease in emission intensity of the nanoplate is observed after 20 h in air. The SCN- passivation during the growth stage of TEA2 SnI4 is proposed to play a crucial role in preventing the oxidation of Sn2+ and hence boosts both stability and photoluminescence yield of tin perovskite nanoplates.

Size Dependent Fluorescence Decay Dynamics of MoS2 Nanoflakes

This paper reports a profound method to prepare MoS 2, and the effect of ultraviolet light irradiation on its emission characteristics. The exfoliation of molybdenum di-sulfide (MoS 2 ) in a liquid phase has been achieved successfully via probe sonication for different time intervals followed by centrifugation method. Ultraviolet–visible (UV–vis) spectra of the obtained MoS 2 dispersions at different exfoliation time indicate that the concentration of MoS 2 nanosheets as well as MoS 2 quantum dots increased remarkably with increasing exfoliation time. We also note that the non-radiative recombination due to UV irradiation on MoS 2 results into the decrease of emission intensity.