The influence of Zn2+ ion on the 1.5 μm laser properties of LiNbO3 crystal heavily doped with Er3+ ion

The spectral characteristics of 1.54 μm emission in a series of Zn/Er:LiNbO₃ crystals with heavy Er content and variable Zn content were reported. The inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the concentration of Er³⁺ ion in the crystal. The absorption and emission spectra of Zn/Er:LiNbO₃ crystals were measured. Based on Judd–Ofelt theory, the spectral parameters such as intensity parameters Ω_t (t=2, 4 and 6), transition strengths, radiative transition probabilities, radiative lifetime and fluorescence branching ratio have been obtained in Zn/Er:LiNbO₃ system. The emission cross section corresponding to ⁴I_13/2→⁴I_15/2 transition of Er³⁺ ion was obtained according to Füchtbauer–Ladenburg theory. The gain cross section of Er:LiNbO₃ crystal codoped with 6 mol% Zn²⁺ ions were also discussed in this work.     

A 2-Hydroxy-1-naphthaldehyde Schiff Base for Turn‐on Fluorescence Detection of Zn2+ Based on PET Mechanism

Journal of Fluorescence - Zinc ion is closely related to human health. Its content in human body is small, while the effect is large. However, it is not the more the better, must be in a scientific...     

Fashionable Co-operative Sensing of Bivalent Zn2+ and Cd2+ in Attendance of OAc− by Use of Simple Sensor: Exploration of Molecular Logic Gate and Docking Studies

Journal of Fluorescence - The Schiff-base probe H2VL [6,6'-((1E,1'E)-hydrazine-1,2 diylidenebis(methanylylidene))bis(2-methoxyphenol)] is synthesized and structurally characterized by...     

Raman Scattering Enhancement Based on High-Pressure High-Temperature Diamonds†

Journal of Russian Laser Research - We discuss the use of high-pressure high-temperature (HPHT) diamonds for the determination of trace amounts of various Raman active substances. The amount of the...     

Influence of ion–ion correlation on Na+ transport in Na2Ni2TeO6: molecular dynamics study

Molecular dynamics (MD) study of Na⁺ transport in Na₂Ni₂TeO₆ is performed systematically with varying strength of Na⁺–Na⁺ short range repulsions to understand the physical principle governing ion transport mechanism. Na⁺ diffusion is enhanced by nearly an order of magnitude with reduced Na⁺–Na⁺ short range repulsion within the studied range. A similar behavior is also observed in other systems, e.g., AgI and Na₂Zn₂TeO₆, where mobile ions are located closely. The Na⁺ ion occupancy in Na₂Ni₂TeO₆ shows a significant shift from Na1 to Na2 sites gaining some degree of correlation. The study also emphasizes how mobile ion size influences the ionic diffusion. The fresh insight such as microscopic migration pathways, energy barriers, and jumping mechanism of Na⁺ are derived from the study.     

AES analysis of nitridation of Si(100) by 2–10 keV N+2 ion beams

Ion beam nitridation of Si(100) as a function of N⁺₂ ion energy in the range of 2–10 keV has been investigated by in-situ Auger electron spectroscopy (AES) analysis and Ar⁺ depth profiling. The AES measurements show that the nitride films formed by 4–10 keV N⁺₂ ion bombardment are relatively uniform and have a composition of near stoichiometric silicon nitride (Si₃N₄), but that formed by 2 keV N⁺₂ ion bombardment is N-rich on the film surface. Formation of the surface N-rich film by 2 keV N⁺₂ ion bombardment can be attributed to radiation-enhanced diffusion of interstitial N atoms and a lower self-sputtering yield. AES depth profile measurements indicate that the thicknesses of nitride films appear to increase with ion energy in the range from 2 to 10 keV and the rate of increase of film thickness is most rapid in the 4–10 keV range. The nitridation reaction process which differs from that of low-energy (< 1 keV) N⁺₂ ion bombardment is explained in terms of ion implantation, physical sputtering, chemical reaction and radiation-enhanced diffusion of interstitial N atoms.     

Effect of hydrostatic pressure and temperature on the EPR spectrum of the Mn2+ ion in Zn(BF4)2 · 6H2O

A study of the effect of hydrostatic pressure and temperature on the EPR spectrum of the Mn²⁺ ion in Zn(BF₄)₂ · 6H₂O is reported. The break in the temperature dependence of the b ₂ ⁰ parameter at 196 K is evidence of the existence of a phase transition accompanied by a change in the thermal expansion coefficient. It is shown that pressure considerably affects the spectral parameters by reducing the axial parameter b ₂ ⁰ and increasing the cubic one, b ₄ ⁰ . At 9 kbar, the b ₂ ⁰ parameter is temperature independent. A comparison of the pressure dependences of the spectra of Zn(BF₄)₂ · 6H₂O, ZnSiF₆ · 6H₂O, ZnTiF₆ · 6H₂O, and MgSiF₂ · 6H₂O crystals suggests equal hydrogen-bond lengths in these compounds. A ligand hyperfine structure has been detected, which originates from the Zeeman interaction with the proton nuclei surrounding Mn²⁺ and manifests itself in the formation of satellites at each EPR line, their separation being proportional to the magnetic field. The nonlinear pressure dependence of the linewidth is related to the structural features of the crystal under study.     

N-benzoate-N′ salicylaldehyde ethynelediamine: A new fluorescent sensor for Zn2+ ion by “off-on” mode

Imbalance of zinc ion (Zn²⁺) in human body causes diseases like Alzheimer’s and Parkinson’s and therefore Zn²⁺ estimation in biological fluids has diagnostic values. Fluorescence “off-on” sensors have advantages of high sensitivity and in situ application over other sensors. A new fluorescent “off-on” Zn²⁺ sensor, N-benzoate-N′ salicylaldehyde ethynelediamine (L), has been synthesisied. In 1:1(v/v) CH₃OH:PBS (PBS?=?phosphate buffer solution), L shows ca. 20 times enhancement in fluorescence intensity on interaction with Zn²⁺, due to snapping of photoinduced electron transfer (PET) process, which is selective over metal ions - Na⁺, K⁺, Ca²⁺, Ni²⁺, Cu²⁺, Cd²⁺, Hg²⁺ and Pb²⁺. These metal ions either individually or all together does not interfere the sensing ability of L towards Zn²⁺. A 1:1 interaction between L and Zn²⁺ ion with binding constant 10^4.25 has been established from spectroscopic data.     

Effect of Process Parameters on Laser Damage Threshold of TiO2 Coatings

We investigate the laser damage behaviour of an electron-beam-deposited TiO2 monolayer at different process parameters. The optical properties, chemical composition, surface defects, absorption and laser-induced damage threshold （LIDT） of films are measured. It is found that TiO2 films with the minimum absorption and the highest LIDT can be fabricated using a TiO2 starting material after annealing. LIDT is mainly related to absorption and is influenced by the non-stoichiometric defects for TiO2 films. Surface defects show no evident effects on LIDT in this experiment.     

Photoluminescence properties of Er-doped β-FeSi2 grown by ion implantation

Photoluminescence (PL) properties of Er-doped β-FeSi₂ (β-FeSi₂:Er) and Er-doped Si (Si:Er) grown by ion implantation were investigated. In PL measurements at 4.2 K, the β-FeSi₂:Er showed the 1.54 μm PL due to the intra-4f shell transition of ⁴I_13/2→⁴I_15/2 in Er³⁺ ions without a defect-related PL observed in Si:Er. In the dependence of the PL intensity on excitation photon flux density, the obtained optical excitation cross-section σ in β-FeSi₂:Er (σ=7×10⁻¹⁷ cm²) is smaller than that in Si:Er (σ=1×10^-15 cm²). In the time-resolved PL and the temperature dependence of the PL intensity, the 1.54 μm PL in β-FeSi₂:Er showed a longer lifetime and larger activation energies for non-radiative recombination (NR) processes than Si:Er. These results revealed that NR centers induced by ion implantation damage were suppressed in β-FeSi₂:Er, but the energy back transfer from Er³⁺ to β-FeSi₂ was larger than Si:Er.     

Comparison of TiO2 and ZrO2 Films Deposited by Electron-Beam Evaporation and by Sol-Gel Process

TiO2 and ZrO2 films are deposited by electron-beam （EB） evaporation and by sol-gel process. The film properties are characterized by visible and Fourier-transform infrared spectrometry, x-ray diffraction analysis, surface roughness measure, absorption and laser-induced damage threshold （LIDT） test. It is found that the sol-gel films have lower refractive index, packing density and roughness than EB deposited films due to their amorphous structure and high OH group concentration in the film. The high LIDT of sol-gel films is mainly due to their amorphous and porous structure, and low absorption. LIDT of EB deposited film is considerably affected by defects in the film, and LIDT of sol-gel deposited film is mainly effected by residual organic impurities and solvent trapped in the film.     

A Remot Sensing Image Compression Method Based on Wavelet Transformation/Vector Quantization

1.IntroductionVectorquantizationprovidesameansofconvertingthedecomposedsignalintobitsinamannerthattakesadvantageofremaininginter--andinter--bandcorrelationaswellasofthemoreflexiblepartitionsofhigherdimensionalvectorspaces.TheimagecompressionmethodofWT VQhasbeenappliedinmanydigitalimageprocessingfields.SubbandcodingwasintroducedbyCroisieretal.inspeechcodingin197611].Croisieretal.firstsolvedthecriticalproblemofaliasingcancellationaf:erdecimationandreconstructioninsubbands,using"Quadraturemirr…     

Effects of Fe2+ content in raw materials on Mn–Zn ferrite magnetic properties

The magnetic properties of Mn–Zn ferrite such as initial permeability, saturation magnetization, Curie temperature, resistivity and power loss are affected greatly by the Fe²⁺ content in the raw materials. The experimental results show that low resistivity (ρ) and high eddy current loss (P_e) are induced by the superfluous Fe²⁺ content in the raw materials; the scant Fe²⁺ content in the raw materials will increase hysteresis loss (P_h) and decrease Curie temperature (T_c), saturation magnetization (M_s) and initial permeability (μ_i).     

Numerical Simulation on Expansion Process of Ablation Plasma Induced by Intense Pulsed Ion Beam

We present a one-dimensional time-dependent numerical model for the expansion process of ablation plasma induced by intense pulsed ion beam （IPIB）. The evolutions of density, velocity, temperature, and pressure of the ablation plasma of the aluminium target are obtained. The numerical results are well in agreement with the relative experimental data. It is shown that the expansion process of ablation plasma induced by IPIB includes strongly nonlinear effects and that shock waves appear during the propagation of the ablation plasma.     

Zn Doping Effect on Magnetic Properties of Znx Cdl-xCr2S4 Systems by High-Temperature Series Expansions

The effect of Zn doping on the magnetic properties of CdCr2S4 systems is studied by mean field theory and high-temperature series expansion （HTSE）. The nearest neighbouring and the next-neighbouring super-exchange interactions Jl（x） and J2（x） are evaluated for the spinel system Zn, Cd1-xCr2S4 in the range 0 〈 x 〈 1. The intra-planar and the inter-planar interactions are deduced. The HTSE combined with the Padd approximant method （PA） is applied to the spinel system ZnxCdl-,Cr2S4. The magnetic phase diagram, i.e. Tc versus dilution x, is obtained. The critical exponents associated with the magnetic susceptibility 7 and the correlation length u are deduced. The obtained theoretical results are in agreement with the experimental data obtained by magnetic measurements.     

Elucidation of mechanisms of ion—molecule reactions by ICR

The mechanisms of some positive and negative ion—molecule reactions have been determined by a quantitative ion cyclotron double-resonance technique with isotopically labelled reactants. Four types of mechanism were elucidated: charge transfer, ion transfer, atom abstraction and complex formation. Thus, charge transfer is shown to be the only major reaction channel in the systems CO⁺ + CO₂, SO⁻ + SO₂, and O⁻ + NO₂, while in the system Cl₂⁻ + Cl₂ CO ion transfer is the main mechanism, and complex formation with oxygen-atom scrambling is the major channel in O⁻ + N₂O.The experimental results also point out cases where the reaction proceeds by more than one mechanism as, for example, in the reaction system H₂O⁺ + H₂O.     

Defects induced by electron irradiation of p-type germanium†

The calculated shapes of blocking dips differ from the experimental ones since models for charged particle motion with in crystals assume a perfect lattice. In this paper we suggest that the difference between the transverse energy distribution π(E⊥) of the particles coming out from a real crystal and that calculated in a statistical equilibrum continuum model, corrected for thermal vibration effects by a diffusion equation, accounts for crystal defects and is approximately independent of the distribution of transverse energy before diffusion and of the energy of blocked particles. The extraction of π(E⊥) from experimental dips requires the inversion of an integral equation, that is analy = tically solved in a particular case of practical interest. This would provide a way of analysing nuclear reaction time measurements that makes use of the full shape of the blocking dips. An illustrative example of the method to a blocking lifetime measurement in ²⁷A1 (p,α) ²⁴Mg resonance reactions is presented.     

Influence of 120 MeV Si9+ ion irradiation on ZnTe semiconductor thin films

ABSTRACT

ZnTe (Zinc Telluride) is a potential semiconducting material for many optoelectronic devices like solar cells and back contact material for CdTe-based solar cells. In the present study, ZnTe thin films were prepared by thermal evaporation technique and then irradiated with 120?MeV Si⁹⁺ ions at different fluences. These films are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV–Visible spectroscopy techniques. XRD study confirms increased crystallinity and grain growth for post-irradiated ZnTe thin films for fluences, up to 1?×?10¹¹ ions cm^?2. However, the grain size and crystallinity decreased for higher fluence-exposed samples. SEM images confirm the observed structural properties. Modification of the surface morphology of the film due to the ion irradiation with different fluences is studied. Optical band gap of film is decreased from 2.31?eV (pristine) to 2.17?eV after irradiation of Si⁹⁺ ions.