Intensity Of Emission Spectra Research Articles

Mechanistic study on 4, 4'-sulfonylbis removal with CO2/Ar gas-liquid DBD plasma

In this study, a single dielectric barrier discharge (DBD) coaxial reactor was used to degrade 4, 4'-sulfonylbis (TBBPS) in water using greenhouse gas (CO2) and argon as the carrier gases. The investigation focused on CO2 conversion, reactive species formation, gas-liquid mass transfer mechanism, and degradation mechanism of TBBPS during the discharge plasma process. With the decrease of CO2/Ar ratio in the process of plasma discharge, the emission spectrum intensity of Ar, CO2 and excited reactive species was enhanced. This increase promoted collision and dissociation of CO2, resulting in a series of chemical reactions that improved the production of reactive species such as ·OH, 1O2, H2O2 and O3. These reactive species initiated a sequence of reactions with TBBPS. Results indicated that at a gas flow rate of 240 mL/min with a CO2/Ar ratio of 1:5, both the highest CO2 conversion rate (17.76%) and TBBPS degradation rate (94.24%) were achieved. The degradation mechanism was elucidated by determining types and contents of reactive species present in treatment liquid along with analysis of intermediate products using liquid chromatography-mass spectrometry techniques. This research provides novel insights into carbon dioxide utilization and water pollution control through dielectric barrier discharge plasma technology.

Exploring single rare earth doped nanophosphor for efficient white emission through codoping of Na+ and Bi3+ ions into Dy3+ activated LaPO4

Using the simple hydrothermal technique, high-purity nanocrystalline Na+ and Bi3+ co-doped Dy3+ activated LaPO4 was effectively prepared. The structural characterisation of the prepared samples was carried out using XRD, EDS, SEM and FTIR analysis. The existence of Na+, Dy3+, La3+, P5+, O2– and Bi3+ was demonstrated using EDS analysis. The direct band gap value of 4.72 eV is obtained from UV visible absorption spectrum and infer that the doped samples are suitable for optical applications. The photoluminescence excitation spectrum monitored at 474 nm and 570 nm emission, the Na+ and Bi3+ co-doped Dy3+ activated LaPO4 exhibit narrow, and intense characteristics f-f peak of Dy3+ ion at 349 nm, 363 nm, 386 nm and 452 nm. Photoluminescence emission spectrum, monitored under 349 nm, 363 nm and 386 nm shows high intense sharp blue emission peaks of Dy3+ with stark splitting at 475 nm, 478 nm, and 486 nm, yellow emission at 571 nm and 580 nm and a very feeble peak at 658 nm in the red region. When the sample is excited at 452 nm only a yellow band is present. Since the intensity of blue and yellow emission in this host matrix is so high and nearly equal, it is appropriate for cool white emission under 350 nm, 363 nm and 386 nm (near UV) excitation and under 452 nm (blue LED) excitation the prepared phosphor may emerge as highly efficient warm white light emitter suitable for general solid-state lighting applications, which can be further confirmed by CIE chromaticity analysis of the prepared sample. In photoluminescence excitation and emission spectra intensities of peaks of the samples with Bi3+ are more intense, this confirms the positive impact of co-doping of Bi3+ into the sample. The Q value from the Dexter’s formula is calculated as an average of 6.4 and is very close to 6 indicates that the interaction is dipole − dipole, which causes the non-radiative energy migration among the Dy3+ ions in the sample. The lifetime of characteristic yellow emission of Dy3+ in the Na+ and Bi3+ co-doped Dy3+ activated LaPO4 host matrix monitored under 350 nm is calculated as 0.642 ms from decay analysis, fitted by a bi-exponential function. The results support the idea that co-doping of Bi3+ and Na+ into the LaPO4:Dy3+ matrix could emerge as a potential white light emitting phosphor for phosphor-converted white LED application.

Vibronic splitting of the electronic origin in two conformers of the 3-tolunitrile dimer.

3-tolunitrile (3-TN) can from three different dimers, which differ in the relative orientation of the methyl groups. We determined the geometry changes of two of these conformers of 3-TN upon electronic excitation via a Franck-Condon fit of the vibronic intensities in the fluorescence emission spectra. Both aromatic rings expand upon electronic excitation, showing a delocalized one-photon excitation of the cluster. The conformer with the smaller COM distance shows an unusual order of the split components of the electronic origin. We attribute this changed order to the stronger CT contributions to the splitting and a partial breakdown of the point dipole approximation, made in the Frenkel type interaction.

Looking into how nickel doping affects the structure, morphology, and optical properties of TiO2 nanofibers

In this paper, we have systematically studied the structural, morphological, and optical properties of Ni-doped TiO2, synthesized via a simple, cost-effective electrospinning method followed by calcination at 500 °C. The nanofibers with a core-shell structure were relatively homogeneous, smooth and randomly oriented, and there were no significant differences in fiber diameters due to Ni2+ content. Core loss mapping using electron energy loss spectroscopy confirmed an even distribution of titanium and relatively uniform nickel in the fibers. It was found that doping with 0.5 mol.% Ni2+ decreased the rutile content, while doping with 1 mol.% Ni2+resulted in a pure anatase phase with a significantly increased specific surface area (36.6 m2/g). Further increase in Ni2+ content (3–10 mol.%) not only prolonged the response of TiO2 nanofibers to visible light, but also increased the specific surface area (49.5 m2/g), decreased crystallite size (7 nm), and increased rutile content in TiO2 (33 wt.%). Photoluminescence analysis revealed that doping TiO2 with different amounts of Ni2+ leads to a gradual decrease of emission spectra intensity and red shift in the maxima positions. The XPS results confirmed that as the Ni2+ content enlarged, the Ti2+ and Ti3+ content increased significantly, effectively promoting the formation of oxygen vacancies. Raman analysis showed that an increase in nickel content (3–5 mol.%) led to a decrease and shift in peak intensity due to Ti3+ formation and also the possible presence of NiTiO3 phases. HRTEM analysis showed that Ni was doped into the substitution sites of both the anatase and rutile TiO2 lattice but had a stronger influence on the distortion of the anatase phase. The photocatalytic activity of Ni-doped TiO2 nanofibers was explored by analyzing the degradation of an antibiotic, oxytetracycline, monitored in laboratory conditions under visible light irradiation. After 60 min of irradiation, the degradation of OTC with 1Ni-TiO2 reached 76.4 % and with 10Ni-TiO2 70.5 %.

Impact of the geometric structure parameter on the performance of dielectric barrier reactor for toluene removal.

The reasonable geometry design of non-thermal plasma (NTP) reactor is significant for its performance. However, optimizing the reactor structure has received insufficient attention in the studies on removing volatile organic compounds by NTP. Several dielectric barrier discharge (DBD) reactors with various barrier thicknesses and discharge gaps were designed, and their discharge characteristics and toluene degradation performance were explored comprehensively. The number and intensity of current pulses, discharge power, emission spectrum intensity and gas temperature of the DBD reactors increased as barrier thickness decreased. The toluene removal efficiency and mineralization rate increased from 23.2-87.1% and 5.3-27.9% to 81.7-100% and 15.9-51.3%, respectively, when the barrier thickness reduced from 3 to 1 mm. With the increase of discharge gap, the breakdown voltage, discharge power, gas temperature and residence time increased, while the discharge intensity decreased. The reactor with the smallest discharge gap (3.5 mm) exhibited the highest toluene removal efficiency (78.4-100%), mineralization rate (15.6-40.9%) and energy yield (8.4-18.7 g/kWh). Finally, the toluene degradation pathways were proposed based on the detected organic intermediates. The findings can provide critical guidance for designing and optimizing of DBD reactor structures.

Study on photoluminescence of integrated nano-calcium carbonate (CaCO3) enhanced with dysprosium (Dy) doped calcium borophosphate (CBP) phosphor

Purpose There is a strong inducement to develop new inorganic materials to substitute the current industrial pigments, which are known for their poor ultraviolet absorbent and low photoluminescence (PL) properties. The purpose of this paper is to invent a better rare-earth-based pigment material as a spectral modifier with good luminescence properties to enhance the spectral response for photovoltaic panel application. Design/methodology/approach Different phosphor samples made of nano-calcium carbonate (CaCO3) with varied wt.% of the dopant Dysprosium doped calcium borophosphate (CBP/Dy) as (W0 – 0%, W1 – 3,85%, W2 – 7.41%, W3 –10.71% and W4 –13.79%) were prepared via the solid-state diffusion method at 600 °C for 6 h using a muffle furnace. The structural, morphological and luminescence properties of the CaCO3:CBP/Dy powder samples were examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and PL test. Findings The XRD, SEM and FTIR results verified the crystalline formation, morphological behaviour and vibration bonds of synthesized CBP/Dy-doped CaCO3 powder samples. XRD pattern revealed that the synthesized powder samples exhibit crystalline structured materials, and SEM results showed irregular shape and porous-like structured morphologies. FTIR spectrum shows prominent bands at 712, 874 and 1,404 cm−1, corresponding to asymmetric stretching vibrations of CO32− groups and out-of-plane bending. PL characterization of CBP/Dy-doped CaCO3 (sample W) shows emission at 427 nm (λmax) under the excitation of 358 nm. The intensity of PL emission spectra drops due to the concentration quenching effect, while the maximum PL intensity is observed in the W3 phosphor powder system. Research limitations/implications This phosphor powder is expected to find out the potential application such as a spectral modifier which is applied to match the energy of photons with solar cell bandgap to improve spectral absorption and lead to better efficiency. Originality/value The introduction of a nano-CaCO3:CBP/Dy hybrid powder system with good luminescence properties to be used as spectral modifiers for solar cell application has been synthesized in the lab, which is a novel attempt.

Fluorescent and electronic properties of Dysprosium acylpyrazolone complexes along with their synthesis and structural features

Six distorted square antiprismatic eight coordinated Dysprosium acylpyrazolone complexes were synthesized having the compositions [Dy(L1)3(EtOH)(H2O)] (DyL1), [Dy(L2)3(EtOH)(H2O)] (DyL2), [Dy(L3)3(EtOH)(H2O)] (DyL3), [Dy(L4)3(EtOH)(H2O)] (DyL4), [Dy(L5)3(EtOH)(H2O)] (DyL5), and [Dy(L6)3(H2O)(EtOH)] (DyL6). The structure of all six complexes was examined using ESI-mass, FT-IR, UV–Vis, powder XRD, and thermogravimetric methods. According to the single crystal analysis of DyL4A, the complex was found eight coordinated (DyO8) with a distorted square antiprismatic geometry. The comparison of stimulated powder pattern of DyL4A crystal and experimental powder x-ray data helps to confirm the geometry of other complexes. In the solid-state emission spectra, the transition 4F9/2→6H13/2, which is close to the yellow region of the visible spectrum (∼510–530 nm), exhibits hypersensitivity. The variance in intensity between electric-dipole and magnetic-dipole transition suggests a less asymmetric environment. The solvent effect has been thoroughly investigated through a comparative analysis of electronic spectra in different solvents. The intensity of emission spectra, Y/B ratio, and antenna effect energy diagram were examined from solid-state emission spectra.

Neodymium based acylpyrazolone complexes: Synthesis and physicochemical characterizations

The electronic spectra of three neodymium acylpyrazolone complexes with the compositions [Nd(DMBPMP)3(H2O)(EtOH)] (Nd1), [Nd(DMMCPMP)3(H2O)(EtOH)] (Nd2), and [Nd(DMBPTMP)3(H2O)(EtOH)] (Nd3) have been analyzed. Utilizing ESI-mass, FT-IR, thermogravimetric, and single crystal X-ray diffraction methods, the structure of the DMBPTMP ligand and all three complexes were investigated. According to the single crystal analysis of Nd2, the complex is mononuclear and eight-coordinate (NdO8) with a distorted square antiprismatic geometry. A powder XRD pattern confirmed a similar structural arrangement of the other two complexes. The transition 4G5/2 ← 4I9/2, which is close to the centre of the visible spectrum (∼17,500 cm−1), exhibits hypersensitivity, which stands out in stark contrast to the behaviour of many other typically weak and reliably unchanging, typical 4f-4f transitions. Through a comparative analysis of calculated oscillator strength, Judd-Ofelt parameters, and covalency parameters in various solvents, hypersensitivity, symmetry characteristics, and covalency have been thoroughly investigated. The promotion of 4f-4f electric-dipole intensity has been found to be particularly successful with DMF, DMSO, pyridine and ethanol. Utilizing Judd-Ofelt parameter Ω4 values and Hirshfeld analysis, long-range secondary π⋯π stacking or H-bonding interactions were investigated. Using solid-state emission spectra, intensity of emission spectra and antenna effect energy diagram was examined.

Comparative Study of Impact of Gamma and MeV Ion Irradiations on Electrical and Optical Properties Polystyrene/Eu2O3 Nanocomposites.

In the present study, the effect of gamma irradiation and 90 MeV carbon ion beam irradiation on electrical properties and optical of Polystyrene/Eu2O3 nanocomposites at different fluences were examined. Modified electrical and optical responses of polymer nanocomposites were investigated using Impedance, Photoluminescence and UV-VIS spectroscopies. FTIR analysis shows a reduction of various modes of molecular vibrations caused by 90 MeV carbon ion beam irradiation. The polymer nanocomposites change into a graphite-like structure upon both kinds of irradiations as evidenced by the decrease in the optical band gap. The photoluminescence emission spectra show three characteristic peaks of Eu3+ ions, when excited at 247 nm wavelength. It emits intense red light suggesting its potential for usage in LED technology. The peak intensity of PL emission spectra is enhanced after ion beam irradiation and is because of the formation new radiative combination; however, it decreases upon gamma irradiation. Dielectric responses of pristine and irradiated polymer nanocomposites were studied over the frequency range of 100 Hz to 100 kHz using LCR meter. There appears a significant improvement in the dielectric response as a result of structural changes in both types of irradiations. AFM images show that the film becomes smoother upon both types of irradiations.

Structural Features, Emission Analysis, and Covalency Comparison of Neodymium Acylpyrazolone Complexes using Oscillator Strengths, Covalency and Judd‐Ofelt Parameters**

AbstractThree distorted square antiprismatic eight coordinated neodymium acylpyrazolone complexes were synthesized having the compositions [Nd(L1)3(H2O)(EtOH)] (NdL1), [Nd(L2)3(H2O)(EtOH)] (NdL2), and [Nd(L3)3(H2O)(EtOH)] (NdL3). The structure of all three complexes was examined using ESI‐mass, FT‐IR, and thermogravimetric methods. According to the single crystal analysis of NdL1, the complex was found eight‐coordinated (NdO8) with a distorted square antiprismatic geometry. A powder XRD pattern confirmed a similar structural arrangement of the other two complexes. In electronic absorption spectra, the transition 4G5/2←4I9/2, which is close to the centre of the visible spectrum (~17,500 cm−1), exhibits hypersensitivity, which stands out in stark contrast to the behaviour of many other typically weak and reliably unchanging, typical 4f–4f transitions. Through a comparative analysis of calculated oscillator strength, Judd‐Ofelt parameters, root mean square deviation, radiative lifetime and covalency parameters in various solvents, hypersensitivity, symmetry characteristics, and covalency have been thoroughly investigated. The promotion of 4f–4f electric‐dipole intensity has been found to be particularly successful with ethanol, pyridine, DMF, and DMSO. Utilizing Judd‐Ofelt Ω4 values and Hirshfeld analysis, long‐range secondary π⋅⋅⋅π stacking or H‐bonding interactions were investigated. The intensity of emission spectra, quantum yield, stokes shift, and antenna effect energy diagram was examined using solid‐state emission spectra.

Crystallization behavior, thermal and fluorescence properties of germanate glass ceramic based on Ga2O3 replacing GeO2

This paper focuses on the effects of Ga2O3/GeO2 ratios and heat treatment on the structure, crystallization and fluorescence properties of Gd2O3-Ga2O3-GeO2-Nd2O3 glass system. According to the results, the glass network's structural stability suffers when the ratio of Ga2O3/GeO2 is low. As the ratio of Ga2O3/GeO2 continues to increase, Ga3+ ions are transformed into [GaO4] to participate in the construction of the glass network structure. The principal phase of glass-ceramics is GdGaGe2O7, and the secondary phase is Ga4GeO8, GeO2 and Gd3Ga5O12. Moreover, the glasses with high content of Ga2O3 is easier to prepare translucent glass-ceramics with uniform grain distribution and size. The emission spectrum intensity of glass-ceramics is obviously improved compared with that of glasses. In addition, it is found that the emission peak of Nd3+ ions generated by 4F3/2 → 4I11/2 electron transition is stably redshifted from 1060 nm to 1088 nm by microcrystallization, which means a small range of spectrum is adjustable.

3D printed Er3+ doped KNNLN piezoelectric ceramics for transparent ultrasonic transducer application

The transparent [Li0.04(K0.5Na0.5)0.96]NbO3+0.5mol% Er2O3 (KNNLN-Er) lead-free piezoelectric ceramics were prepared by stereolithography technique. The influence of different sintering holding time (4h∼8h) on the micromorphology, relative density, shrinkage, electric properties, and photoluminescence properties were systematically investigated. The KNNLN-Er ceramics show the coexistence of orthorhombic and tetragonal structures. The grain size increases obviously and then decreases slightly with the holding time increasing. The KNNLN-Er ceramics exhibit good piezoelectric performance (piezoelectric constant d33∼97 pC/N, electromechanical couple coefficient kt∼0.36) and the moderate transparency of 34% when the holding time is 6h during sintering at 1120°C. Besides, the intensity of the photoluminescence emission spectra increases with the holding time increasing. Furthermore, in order to estimate the properties of the KNNLN-Er transparent ceramics, an ultrasonic transducer with a center frequency of 10.5 MHz was fabricated, which can be used for photoacoustic and fluorescence imaging. The results indicate that the KNNLN-Er ceramics have potential for multimode imaging applications.

Effect of pulse duration on the above-threshold ionization of a hydrogen atom irradiated by a 400 nm intense laser.

The photoelectron emission spectra generated by the interaction between ultrashort intense laser pulses and atoms can reveal the ultrafast dynamics of electrons. By using the numerical solution of the time-dependent Schrödinger equation in momentum space, the photoelectron emission spectra of atoms irradiated by 400 nm intense lasers with different durations of the pulse has been investigated. In the photoelectron emission spectrum, in addition to the above-threshold ionization peaks due to ionization interference in multiple cycles and the sideband peaks mainly due to the interference of ionized electrons at different moments along the rising edge of the laser pulse envelope, additional peaks of photoelectron emission whose intensity appears to oscillate with the increasing duration of the laser pulse can also be observed. Based on strong-field approximation and the population's analysis of the bound state, it is found that these photoelectron peaks originate from the ionization of the excited state and the oscillations of these peaks are due to the superposition of their peak energy positions with the sideband energy positions. Furthermore, it is demonstrated that the energy positions of the maximum intensity of the photoelectron emission spectra move towards the higher energy end as the duration of the driving laser pulse extends. This phenomenon can be attributed to the fact that the main moment of ionization of atoms changes with the increasing duration of the driving laser pulse, thus allowing the real-time ionization of atoms to be probed using photoelectron emission spectra.

Luminescence characteristics of Dy3+ doped sodium alumina borate glass: Role of silver

Metallic nanoparticle (NP) doped glasses have been studied as promising candidates for various technological applications due to their ability to improve the luminescence properties of rare earth ions. In this work, Dy2O3 and Ag2O co-doped sodium alumina borate glasses were synthesized by conventional melt-quenching technique. Raman analysis verified the existence of [BO3] and [BO4] groups with B–O stretching vibrations in the prepared glasses. Transmission electron microscope images confirmed the presence of spherical Ag NPs, whose average diameter is about 7.60 nm, in H-0.5Dy1Ag glass matrix. The optical and luminescence properties were investigated according to Ag concentrations. The negative value of the bonding parameters, calculated from the absorption spectra, indicates the ionic nature between the Dy3+ ions and its surrounding ligands. In order to determine the nature of the Dy-O bond and the symmetry around the Dy3+ ion environment, Judd–Ofelt intensity parameters (Ω λ, λ = 2, 4, 6) were obtained from the absorption spectra. The luminescence spectra obtained under 350 nm excitation exhibits four emission bands at 481 (4F9/2→6H15/2), 572 (4F9/2→6H13/2), 662 (4F9/2→6H11/2), and 750 (4F9/2→6H9/2) nm. The intensity of emission spectra increases with Ag2O content until 1.0 wt% in H-0.5Dy-yAg glasses and then decreases due to the back-energy transfer (ET) from Dy3+ to Ag+. The ET mechanism from Ag+ to Dy3+ ion for H-1Ag-xDy glasses were investigated through Forster-Dexter’s theory and were found to be quadrupole-quadrupole type. The various radiative properties were calculated by using Judd-Ofelt intensity parameters and emission spectra. It was found that the 572 nm emission band, located in the yellow region, has higher radiative parameters. As a function of Ag concentration, the Y/B values, Commission Internationale d’Eclairage (CIE) chromaticity coordinates (x,y) and correlated color temperatures (CCT) were evaluated. The CIE chromaticity coordinates and CCT values of all glasses are located in the white light region. The decay time values of 1S0→3D1 transition of Ag+ ions and 4F9/2→6H13/2 transition of Dy3+ ions confirm the ET from Ag+ to Dy3+ ions. Overall, the present study indicates that the synthesized glasses with Ag addition exhibits improved luminescence, making them potential candidate for white LEDs.

Post-functionalization of graphitic carbon nitride for highly efficient photocatalytic hydrogen evolution

In this work we report the feasible modification of graphitic carbon nitride (g-C3N4) polymer through a post-functionalization progress. The resultant photocatalyst exhibits boron doping and mesoporous structure with a high surface area of 125 m2/g, leading in an increased surface activity for photocatalytic water splitting reaction. X-ray diffraction, X-ray photoelectron spectroscopy, PL emission spectra and UV-Vis spectra were used to detect the properties of as-prepared samples. Based on X-ray photoelectron spectroscopy analysis, boron is proposed to dope in the g-C3N4 lattice. Optical studies indicated that boron doped g-C3N4 exhibits enhanced and extended light absorbance in the visible-light region and a much lower intensity of PL emission spectra compared to pure g-C3N4. As a result, boron doped g-C3N4 shows activity of 10.2 times higher than the pristine g-C3N4 for photocatalytic hydrogen evolution. This work may provide a way to design efficient and mesoporous photocatalysts through post modification.

Spectral properties of B40 enhanced by small molecule adsorption.

The luminescence characteristics of small molecule excited B40 have not been studied yet, and it may have a potential application value in quantum dot luminescence. Herein, the adsorption and fluorescence emission spectra of small molecules (pyridine, pyrazine and benzene) adsorbed on B40 are studied using first-principles. The results show that the absorption of pyridine and pyrazine on B40 can form stable chemisorption structures pyridine-B40 and pyrazine-B40, while benzene adsorption can form physisorption structure benzene-B40. Moreover, the adsorbed pyridine can enhance the intensity of emission spectra of B40. And the pyrazine adsorbed can obviously enhance the intensity of absorption and emission spectra of B40 and cause the spectra to redshift to the visible light range. And the adsorption of benzene has almost no enhancement effect on absorption and emission spectra of B40. In addition, the influence of different computational basis sets on spectra characteristics has also been discussed and the results show that the main peaks of absorption and emission spectra calculated by the diffuse function augmented basis sets are redshifted relatively. This finding provides a strategy for quantum dot luminescence and a theoretical reference for experimental research.

Green synthesis, structural and luminescent characterization of BaZrO3:Eu3+ nanoparticles

This paper presents experimental results of the structural, morphological, and luminescence characterization of Eu 3+ doped BaZrO 3 powders produced by the green synthesis method. The highly crystalized cubic structure perovskite powders of the formula BaZrO 3 were synthesized by the chemical hydrothermal method. The phase of the compound and the average particle size were determined using X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Powder samples were characterized also by photoluminescence (PL) and thermoluminescence (TL) techniques. Results showed that BaZrO 3 crystallizes in its perovskite cubic phase, with a crystal size circa 40 nm. The presence of each element of the compound was confirmed by the energy disperse spectroscopy (EDS) technique. The PL emission spectra, at room temperature, were obtained using 395 nm as excitation wavelength. The spectra showed the characteristic emissions of Eu 3+ ion. The intensity of the PL emission spectra varies with the Eu 3+ concentration and shows a maximum luminescence efficiency when the synthesis of BaZrO 3 was performed using a content of 5 mol% Eu³⁺. The thermoluminescence data shows that at the heating rate of 10 °C/s, BaZrO 3 :Eu 3+ doped with 5% of dopant concentration exhibits two TL peaks: first of them rapidly decaying peaks at about 110 °C and a high sensitivity peak at 235 °C TL. The correlation between luminescence intensity and concentration quenching of the prepared phosphor was investigated. Present findings substantiate the ability of the BaZrO 3 nanopowder sample to be a promising candidate for luminescence applications.

Structural change dynamics of heteroleptic Cu(I) complexes observed by ultrafast emission spectroscopy.

[Cu(I)(dmp)(P)2]+ (dmp = 2,9-dimethyl-1,10-phenanthroline derivatives; P = phosphine ligand) is one of the most promising photosensitizers used in a photo-catalytic system for reducing CO2, for which the quantum yield is as high as 57%. In this work, time-resolved emission spectra of Cu(I) complexes in solutions were investigated using femtosecond fluorescence up-conversion and nanosecond time-resolved emission spectroscopic systems. The temporal profiles of emission intensities less than 10 ps in acetonitrile solution were reproduced using a tri-exponential function with three-time constants of 0.040 ps, 0.78 ps and 8.0 ps. We found that only the second time constant is dependent on the solvent (acetonitrile: 0.78 ps, butyronitrile: 1.4 ps), indicating that the 0.78 ps spectral change is attributed to the structural change of the Cu(I) complex. The oscillator strengths of transition species are derived from the intensities in the time-resolved emission spectra (species-associated spectra). Based on the oscillator strengths, we concluded that the 0.040 ps process is the Sn → S1 internal conversion and the 0.78 ps process is a structural change in the S1 state. The final time constant of 8.0 ps is assigned to the S1 → T1 intersystem crossing because the 3MLCT state (τT1 = 97 ns) is generated after the decay. The DFT calculation showed that the 0.78 ps spectral change (∼600 cm-1 redshift) is attributed to Jahn-Teller distortion around the metal center, and there is a large structural change in the ligand, which results in a large Stokes shift in the Sn state (7.3 × 103 cm-1).

<i>In situ</i> study of light emission from SiO<sub>2</sub> irradiated by 645 MeV Xe<sup>35+</sup> ions

Silicon dioxide (SiO<sub>2</sub>) is an important component of nuclear reactor optical fiber and is also a candidate material for wast solidification. Owing to its special physical and chemical characteristics, it is used in many different technology fields like optics, electronics, energy orspace. Swift heavy ion irradiation can modify the crystal structure and optical property of optical material SiO<sub>2</sub>. Swift heavy ions deposit their energy mainly by inelastic interaction. Highly ionized lattice atoms may be formed along the trajectory, and a fraction of their electrical energy can be converted directly into the kinetic energy of the ions. The irradiation experiment is performed with Xe<sup>q+</sup> ions at the irradiation terminal of the sector-focused cyclotron at heavy-ion research facility in Lanzhou (HIRFL). The on-line spectral measurement experiment is carried out during irradiation. In the darkroom, the UV-visible light emission from the target is focused into optical fiber by a collimating lens, and then is analyzed with the Sp-2558 spectrometer equipped with a 1200 g/mm optical grating blazed at 500 nm. In the present work, SiO<sub>2</sub> single crystals are irradiated with 93–609 MeV Xe<sup>q+</sup> ions with a dose in a range of 1×10<sup>11</sup>–3×10<sup>11</sup> ions/cm<sup>2</sup>. During irradiation, the emission spectra, in a range of 200–800 nm, from SiO<sub>2</sub> irradiated by 93, 245, 425 and 609 MeV Xe<sup>q+</sup> ions, are obtained. Two emission bands centered at 461 and 631 nm are observed. These emission bands are produced by Frenkel exciton radiation de-excitation and their intensities are closely related to the irradiated ion energy and radiation dose. The results show that the light intensity increases with the electron energy loss index increasing. And owing to crystal damage caused by ion irradiation, the intensity of emission spectrum decreases with the augment of irradiation dose. Ion loses its energy throughout the ion track via Sn and Se interacting with target atoms and electrons respectively, and the energy lost by the ion is estimated by using SRIM code. The SRIM simulated ion ranges and recoil atom distribution, target ionization (energy loss to target electrons), damage production in SiO<sub>2</sub> are presented. Based on the energy deposition process, the emission bands related to the crystal structure itself are discussed. It indicates that electron energy loss plays a leading role in the process of light emission. In-situ measurement of the optical emission is of great significance in studying the irradiation modification and can help to understand the process of crystal damage caused by ion irradiation.

Discharge Characteristics and Hydrogen Peroxide Generation of Multi-Needles Plate Discharge Under Pulsed Power

In this article, discharge characteristics and hydrogen peroxide (H2O2) generation of multi-needles plate discharge under pulsed power are investigated. By changing the voltage peak value, the pulse repetition frequency, voltage rising edge time, and the number of needles, the change laws of discharge characteristics, molecular emission spectrum, and H2O2 concentration are studied. The results show that as the number of needles increases, the discharge power increases. Through the emission spectra showed, the emission spectrum intensity of OH ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{A}^{2}\sum + \to \,\,\text{X}^{2}\prod $ </tex-math></inline-formula> , 0–0, 309 nm) and N2 ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{C}^{3}\prod \text{u}~\to ~\text{B}^{3}\prod \text{g}$ </tex-math></inline-formula> , 0–0, 337 nm) also increases with the number of needles. The changes in the vibrational temperature and rotational temperature of N2 molecules show a steady process. As the number of needles increases, the vibrational temperature is 2835–3100 K and the rotational temperature is 342–410 K. They all belong to the low-temperature plasma range. As the number of needles increased, the concentration of H2O2 in the solution also increased. The concentration of H2O2 in the solution corresponds to the emission spectrum intensities of OH ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{A}^{2}\sum + \to \,\,\text{X}^{2}\prod$ </tex-math></inline-formula> ). When the peak value is 14 kV, the pulse frequency is 1 kHz. The maximum concentration of H2O2 reached 15.277 mg/L with 14 needles.