Emission Relative Intensity Research Articles

On the modulation/energy competing of Tb(III)/Eu(III) emission in microporous MOF host for peroxide recognition

Being an important chemical reagent having moderate oxidizability, peracitic acid (PAA) has been applied in modern industries and processing, as well as public safety. These versatile applications make PAA an important analyte to be precisely and sensitively detected. The present work chose the combination of rare-earth-based probe and a microporous host bio-MOF-1 ([Zn8(ad)4(BPDC)6O·2(Me2NH2)+]·G, ad = adenine, BPDC = 4,4′-biphenyl dicarboxylic acid, G = N,N-dimetylformamide and water). Two β-diketone ligands, 1,3-di(pyridin-3-yl)propane-1,3-dione (DPY) and 1,3-diphenylpropane-1,3-dione (DPP), were coordinated to Tb(III) and Eu(III) ions to form probe [RE(DPY/DPP)2]Cl which was loaded into bio-MOF-1 micropores with different loading contents via an ionic exchange operation. The resulting composite samples were fully characterized, including synthesis, morphology, composition, sensing performance and mechanism. The protonation/oxidization of DPY and DPP ligands adjusted their triplet energy level (T1) and consequently affected their energy transfer (ET) efficiency to RE ions, resulting in the variation of RE emission relative intensity. A new pathway for PAA optical sensing was thus proposed. Linear fitting equations were observed for DPY-based samples, showing fluorescence intensity ratio value of 8.80, response time of 9 s, and LOD of 8.08 μM within working region of 0–140 μM.

Energy transfer from Mn2+ to Nd3+ ions embedded in a nanostructured glass system with Zn1−xMnxTe nanocrystals

In this work, we study energy transfer (ET) processes between Mn2+ and Nd3+ ions in Nd2O3-doped P2O5–ZnO–Al2O3–BaO–PbO glass system, nanostructured with Zn1−xMnxTe diluted magnetic semiconductor nanocrystals (NCs), aiming nanotechnology applications. Transmission electronic microscopy (TEM), X-ray diffraction (XRD), optical absorption (OA), photoluminescence (PL), and lifetime measurements were performed for a complete characterization of the investigated materials. The TEM and XRD data confirm the formation of Zn1−xMnxTe NCs in the host glass system. The overlap between the Mn2+ ion emission band and the Nd3+ ion absorption bands suggests that an efficient resonant type energy transfer from Mn2+ to Nd3+ ions is expected. PL spectra show that the characteristic emission relative intensities of Nd3+ ions increase systematically with increasing Mn concentration. Indeed, the 4T1(4G) state lifetime of Mn2+ ions gradually decreases with rising Mn concentration. This result confirm the evidence on ET from Mn2+ ions to Nd3+ ions. In addition, the increase in the 4F3/2 state lifetime is an evidence of persistent luminescence due to the presence of Mn2+ ions.

Laser induced breakdown in pulsed helium atmospheric pressure plasma jet

This study connects two fields of research: laser induced plasmas and nonequilibrium low-temperature plasmas by studying effects of preionisation, made by a single-electrode atmospheric pressure plasma jet, on a laser induced breakdown (LIB) in helium. A laser pulse (1064 nm, 4 ns pulse width, 5 Hz repetition rate) was focused into the helium jet flowing into ambient air and synchronized with the discharge (10 kHz repetition rate). The level of preionisation in the focal volume at the moment when the laser pulse arrives was controlled by changing the time delay between voltage and laser pulse. The conditions of the discharge are strongly affecting laser induced plasma by providing initial seed of electrons and promoting the breakdown in helium. Measurements of the absorbed laser pulse energy and optical emission relative intensities were performed for different time delays between voltage and laser pulse. Study of LIB with preionisation is discussed as a potential tool for diagnostics of free plasma jets and jets interacting with various target materials.

Spectroscopic diagnosis of plasma in atmospheric pressure negative pulsed gas-liquid discharge with nozzle-cylinder electrode

The plasma characteristics of a gas-liquid phase discharge reactor were investigated by optical and electrical methods. The nozzle-cylinder electrode in the discharge reactor was supplied with a negative nanosecond pulsed generator. The optical emission spectrum diagnosis revealed that OH (A2∑+ → X2Π, 306–309 nm), N2 (C3Π→B3Πg, 337 nm), O (3p5p→3s5s0, 777.2 nm) and O (3p3p→3s3s0, 844.6 nm) were produced in the discharge plasma channels. The electron temperature (Te) was calculated from the emission relative intensity ratio between the atomic O 777.2 nm and 844.6 nm, and it increased with the applied voltage and the pulsed frequency and fell within the range of 0.5–0.8 eV. The gas temperature (Tg) that was measured by Lifbase was in a range from 400 K to 600 K.

Strain-Induced Enhancement of Eu3+ Emission in Red Phosphor NaMgPO4:Eu3+, Al3+

A series of (NaMgPO4)0.98−x : $${\hbox{Eu}}_{0.02}^{3 + }$$ , $${\hbox{Al}}_{x}^{3 + }$$ phosphors were prepared by the solid-state method. X-ray powder diffraction results confirm that the samples contain mixture phases of crystals. The doped effect of Al3+ on the photoluminescence properties of (NaMgPO4)0.98−x : $${\hbox{Eu}}_{0.02}^{3 + }$$ , $${\hbox{Al}}_{x}^{3 + }$$ phosphors is discussed. The results indicate that two dependent curves of emission relative intensity and strain on Al3+ doping concentration are all Gaussian curves, and a high correlation is observed between emission relative intensity of Eu3+ and strain caused by Al3+. In other words, emission relative intensity of Eu3+ is enhanced with the increase of the strain. The enhanced mechanism of the strain is discussed. In addition, (NaMgPO4)0.98−x : $${\hbox{Eu}}_{0.02}^{3 + }$$ , $${\hbox{Al}}_{x}^{3 + }$$ phosphors are electric dipole-dominated transition red phosphors. The optimal molar concentration of Al3+ for the samples is 9%, which (NaMgPO4)0.89: $${\hbox{Eu}}_{0.02}^{3 + }$$ , $${\hbox{Al}}_{0.09}^{3 + }$$ is a potential candidate as the red-emitting phosphor for ultraviolet-based white light-emitting diodes.

Characterization of atmospheric pressuredc gliding arc plasma

The atmospheric pressure dc gliding arc plasma was investigated through its electrical and optical signals. The arc voltages of various gas discharges were compared. The arc voltage, current, power and resistance of a nitrogen gliding arc in one period were studied. Influences of gas type, gas flow rate and external resistor on the gliding arc fluctuation behaviour were studied using FFT spectrum analysis. Increased main oscillation frequency was observed as gas flow rate or external resistance value increased. Furthermore, major radical species in nitrogen, oxygen and air discharges were determined by means of optical emission spectroscopy. Additionally, the effect of external resistor on the relative intensity of radical emission and axial distribution of relative intensity at 337.1 nm (N2(C3Πu→B3Πg), Δv=0) were studied. Experimental results showed that radical emission relative intensity decreases with the increasing of external resistance value. The axial distribution of relative intensity exhibits the tendencies of increasing first and then decreasing. The radical emission relative intensity decreases dramatically out of the plasma area.

White-Emitting Phosphor Ca2BO3Cl : Ce3 + , Eu2 + for UV Light-Emitting Diodes

and coactivated phosphors exhibit two blue and yellow emission bands under the excitation of UV light. An asymmetric blue emission originates from , whereas the yellow emission originates from . The luminescent mechanism is explained by the resonance-type energy transfer from to , and the energy-transfer efficiency is also calculated by decline and growth of their emission relative intensities. In light of the principle of energy transfer, the varied emitted color of phosphor from blue through white and finally to yellow can be achieved by properly tuning the ratio of .

White Light–Generation Phosphor Ba2Ca ( BO3 ) 2 : Ce3 + , Mn2 + for Light-Emitting Diodes

and co-doped phosphors have been prepared at under a reduced atmosphere, and their luminescence properties have also been investigated by tuning the concentration of activators. White light-emitting phosphors excited with UV or violet light could be obtained in and coactivated phosphors by adjusting contents appropriately. Two types of centers, occupying the and sites, respectively, emit blue and green light, whereas the enters the sites and emits red light. The energy transfer involving , , and have also been observed by analyzing their photoluminescence (PL) and PL excitation spectra. The energy transfer efficiencies from different sites to were calculated by decline and growth of their emission relative intensity. In light of the principle of energy transfer and appropriate tuning of activator contents, we demonstrated that : , is potentially useful as an UV or near-UV convertible phosphor for white light–emitting diodes. Moreover, their CIE chromaticity coordinates, color temperature, and color-rendering index Ra have also been calculated according to corresponding PL spectra under 345 and radiation.

Er, Yb Doped Yttrium Based Nanosized Phosphors: Particle Size, “Host Lattice” and Doping Ion Concentration Effects on Upconversion Efficiency

The upconverter phosphors studied herein have different percentages of Er3+ and Yb3+ as doping ions in different Y3+ matrixes (Y2O3, Y2O2S), and were prepared from different precursors (polymeric resin, oxalate, basic carbonate) and method (combustion). Upconversion emission spectra were recorded at 298 K for all the doped samples in the visible region, for efficiency and Green/Red emission relative intensity comparisons. Therefore, an investigation of the influence of the doping ion concentration, particle size and host lattice on the upconversion process is provided in view of the UPT (Upconverting phosphor technology application). On the basis of the results, it was possible to evaluate the best combination for a specific assay, considering whether it is advantageous to have the greatest contribution from the green or red emissions, or from both in comparable intensities.