Comparison of optical properties of Cu-Al_2O_3 and Ag-Al_2O_3 nano-array composite structure

Cu-Al2O3 (Ag-Al2O3) nano-array composite structures were obtained by alternating current (AC) elec-trodeposition Cu (Ag) into the pores of anodic alumina. Their transmitted spectra and polarized properties were investigated in detail. Experimental results indicate that the transmittance of Cu-Al2O3 is superior to that of Ag-Al2O3 in visible and infrared wavebands, and the extinction ratio is better than that of Ag-Al2O3 in near infrared waveband.     

Determination of Nonlinear Optical Coefficients of KBe2BO3F2 Crystals

Considering that KBe2BO3F2(KBBF) is an outstanding deep ultraviolet crystal which can generate the shortest wavelengths in second harmonic generation and sum-frequency generation,we report the determination of the nonlinear optical coefficients of the KBBF crystal.The d11 coefficient was determined to be 0.49pm/V by the Maker fringes method at the wavelength 1064nm,which is in agreement well with the theoretical value.     

Spectroscopic properties of Er~(3+)-doped AlF_3-La_2O_3-Al_2O_3-SiO_2 glasses

Er~(3+)-doped fluoride lanthanum aluminosilicate glasses with compositions of (65-x/2)SiO_2·(25-x/2)Al_2O_3·xAlF_3·9.1La_2O_3·0.6Er_2O_3·0.3Yb_2O_3(x=4, 8, 12, 20, 30) (mol%) were prepared and their glass transition temperatures and spectroscopic properties were investigated.The Ω_2, Ω_4, and Ω_6 intensity parameters of glasses were calculated by Judd-Ofelt theory from absorption curves. It was found that glasses transition temperature and melting temperature decreased with the increase of fluoride content in glass,Ω_2 decreased gradually with the increase of AlF_3 content,but both Ω_4 and Ω_6 did not increase until AlF_3 content increased to 30 mol%.The quantum efficiency of ~4I_(13/2) to ~4I_(15/2) transition of Er~(3+) ions increases with the increase of AlF_3 content in glass.Fluorescent lifetime is longer in glass containing more AlF_3 content.     

Radiation-stimulated changes in the transmission of chalcogenide glasses of As2S3−Ge2S3

The radiative-optical properties of chalcogenide glass-like semiconductors of the As₂S₂−Ge₂S₃ system in the region of a topological 2D-3D-phase transition are investigated. It is shown that γ-irradiation of samples by an absorbed dose of 4.4 · 10⁶ Gy leads to a longwave shift of their optical-transmission edge in the spectrum. The effect observed depends on the structural type of the glasses investigated and changes considerably near the 2D-3D-phase transition. Two components of the transmission-edge shift are detected: a static component, which remains unchanged for a long time after irradiation of the samples, and a dynamic one, which gradually fades in 2–3 months. It is suggested that the microstructural mechanism of these changes is attributable to processes of coordination defect formation in the structural skeleton of the samples. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, pp. 657–660, September–October, 1999.     

Specific Features of the Local Structure and Transport Properties of ZrO2–Sc2O3–Y2O3 and ZrO2–Sc2O3–Yb2O3 Crystals

Optics and Spectroscopy - The specific features of the local structure of ZrO2–Sc2O3–Y2O3 and ZrO2–Sc2O3–Yb2O3 crystals are revealed by optical spectroscopy using the Eu3+...     

Calculation of Electron-Impact 2s^2 2p^4 ^3P→2p^3 3s^3S^0 Transition in Atomic Oxygen

The inelastic scattering of electron from oxygen for the 2s^2 2p^4 ^3P→2p^3 3s^3S^0 transirion is studied using the momentum-space coupled channel optical method at 15, 17.5, 20, 22.5, 25, 27.5, 30, 50, and 100eV. Direct ionization cross sections, i.e. differential and integral cross sections, are reported. Important continuum states are included in the coupled channel calculation via a complex equivalent-local optical potential. The present results are compared with the available experimental data and other theoretical calculation results.     

Assignment of Isodoublet of 2^3S1 Meson Nonet

Inserting the masses of some states, which have been established in theexperiments or the theory of lattice QCD, we investigate the mass of theisodoublet of the 2³S₁ meson nonet. The agreement results, 1567±22.6MeV and 1576.8MeV, are given by two different approaches. We suggest that the assignment of 2³S₁ meson nonet should be re-examined in future experiments.     

Investigation of emission properties of Tm3＋：Y2O3 transparent ceramic

A transparent and emitting ceramic of Y 2 O 3 doped with 6% Tm 3+ ions is fabricated by vacuum sintering with ZrO 2 . Absorption, photoluminescence (PL), and PL excitation (PLE) spectra are investigated in a spectral range of 200 to 2 100 nm at various temperatures between 296 and 12 K. Intense emission band appears at 450 to 465 nm in the visible range. Near-infrared emission bands are observed at 1 200 to 1 300 nm and 1 400 to 1 550 nm, with intense peaks at 1 270, 1 450, and 1 523 nm. The luminescence mechanisms and potential applications of the emissions are discussed with the help of Judd-Ofelt theory and PLE spectra.     

Influence of different Fe2O3 content on crystallization of MgO–Al2O3–SiO2–TiO2 system glass-ceramics

The crystallization behaviors of MgO–Al₂O₃–SiO₂–TiO₂ system glasses doping with different content Fe₂O₃ were investigated by means of differential thermal analysis and X-ray diffraction. The kinetic parameter of activation energy for crystallization (E) was obtained by the Owaza Johnson–Mehl–Avrami method. The results show that during the heat treatment, the intermediate phase of µ-cordierite initially precipitated from the glass matrix, and with the increasing temperature, it transformed to α-cordierite. The more the Fe₂O₃ content, the lower the crystallization peak temperature (T _p).But the lowering of T _p value did not mean that the value of E decreases correspondingly. The experimental results suggest that only with appropriate content (about 4.2 wt%), Fe₂O₃ can promote the crystallization of this glass effectively.     

Vibrational spectra of an LiNO3–(CH3)2SO2 system

Raman and IR absorption spectra were studied and molecular relaxation characteristics of vibrations of the anion and solvent were calculated for an xLiNO₃–(1 – x)(CH₃)₂SO₂ system (x = 0.1, 0.2, 0.3, 0.4 M). It was found that it is impossible to increase the concentration of free ions involved in charge transfer in such a system by either increasing the temperature or changing the concentration composition in the studied range of x.     

A computational study of the electron detachment energies of Al2As2 − and Al3As3 −

Ab initio and density functional theory calculations are reported for the low-lying electronic states of Al₂As₂ ^?, Al₂As₂, Al₃As₃ ^?, and Al₃As₃. The ²B_2g ground electronic state of Al₂As₂ ^? has a rhombic structure with the Al atoms occupying the shorter diagonal. In contrast, the As atoms occupy the shorter diagonal of the ground state rhombic structure of Al₂As₂. Electron detachment energies computed for Al₂As₂ ^? are presented and discussed. The adiabatic electron affinity of Al₂As₂ ^? is calculated to be 2.1 eV at the CCSD(T) level, using B3LYP and MP2 optimized geometries. The ground states of both Al₃As₃ ^? (²A₁′) and Al₃As₃ (¹A₁′) have planar hexagonal D_3h geometry. Electron detachment energies computed for the anion are reported. At the CCSD(T)//B3LYP level, the electron affinity of Al₃As₃ is calculated to be 2.47 eV.     

Analysis of the Vibrational-Rotational Structure of 2ν1, ν1 + ν3, and 2ν3 Bands of the D2Se Molecule

The absorption spectrum of the D₂Se molecule in the region of 2₁, ₁ + ₃, and 2₃ absorption bands is registered with a high-resolution Fourier spectrometer and is studied theoretically for a Hamiltonian model with allowance for resonant interactions among (200), (101), and (002) vibrational states.     

Theoretical calculations of N2-broadened half-widths of ν5 transitions of HNO3

A number of satellite instruments are measuring nitric acid, HNO₃, in the Earth's atmosphere. In order to do retrievals of temperature and concentration profiles, the spectral parameters for many thousands of HNO₃ transitions must be known. Currently the HITRAN database uses a constant estimated value for the air-broadened half-width of HNO₃. To help improve the line shape parameters, complex Robert–Bonamy calculations were made to determine N₂-broadened half-widths for some 5000 transitions of HNO₃ in the ν₅ band. The intermolecular potential is a sum of electrostatic terms (dipole–quadrupole and quadrupole–quadrupole) and the atom–atom potential expanded to eighth order. The trajectory parameters were adjusted to yield better agreement with measurement. Velocity integrated calculations were made at seven temperatures in order to determine the temperature dependence of the half-widths. The half-width data are compared with available rotation band measurements. The average percent difference between the measured and calculated half-widths is ?2.38 for N₂-broadening and ?0.65 for air-broadening. The temperature, vibrational, and rotational state dependence of the half-width are investigated.     

Composition Dependence of Spectroscopic Properties of Er^3＋ Doped TeO2-WO3-ZnO Glasses

Er^3 -doped TeO2-WO3-ZnO glasses were prepared and the absorption spectra, emission spectra and fluorescence lifetimes were measured. With more Te02 content in the glasses, the emission full width at half maximum (FWHM) increases while the lifetime of the ^4I13/2 level of Er^3 decreases. The stimulated emission cross-sectionof Er^3 calculated by the McCumber theory is as large as 0.86pm^2. The product of the FWHM and the emissioncross-section σe of Er^3 in TeO2-WO3-ZnO glass is larger than those in other glasses, which indicates that the glasses are promising candidates for Er^3 -doped broadband amplifiers. The Judd-Otfelt parameter Ω6 shows close composition dependence of the 1.5μm emission bandwidth. The more the TeO2 content is, the larger thevalues of Ω6 and FWHM.     

Effects of Y_2O_3 upon mechanical properties of laser coating

The biomedical materials, due to their mechanical prop-erties such as bending strength, compressive strength,tensile strength, hardness and so forth, are prerequisiteto substitutions for the biological organs or tissues, inparticular, for the hardness tissue which need endure ortransfer the loading. Laser cladding calcium phosphate(Ca-P) coating on alloy Ti-6A1-4V (TC4) is a promis-ing bioceramic material[1-3], which is potentially used inorthopedic and dental implants, due to it nice biocom…     

Identification of the 3s 2 3p 2 3 P 1,2 — 3s3p 3 5 S 2 0 intercombination transition in siliconlike Ni14+

The³P1, 2^{? 5}S ₂ ^o intercombination lines in Ni¹⁴⁺ have been identified in the EUV spectrum emitted by foil-excited Ni ion beams. The wavelengths are close to the theoretically predicted values. The relative intensities of the lines confirm the predicted branching ratios. In a most recent paper Ellis and Martinson [1] give predicted wavelengths and transition rates for the 3s²3p^{2 3}P_1,2 — 3s3p^{3 5}S ₂ ^o , intercombination transition in siliconlike ions with 16≤Z≤28. The data were obtained theoretically (and compared with other theoretical data by Huang [2]) but adjusted to match the known wavelengths of this transition in the first three ions of the sequence and the finestructure intervals of the³P state which are known for a few more ionization stages.     

Spectroscopic Properties of Er3+/Yb3+-codoped PbO–Bi2O3–Ga2O3–GeO2 Glasses

We investigate the spectroscopic properties of the 1.5-μm emission from the ⁴I_13/2 → ⁴I_15/2 transition of Er³⁺ ions in PbO–Bi₂O₃–Ga₂O₃–GeO₂ glasses for applications in broadband fiber amplifiers. The measured emission peak locates at 1,532 nm with a full width at half-maximum of ∼45 nm. The glasses exhibit a large stimulated emission cross-section of 0.89 × 10⁻²⁰ cm² and a large product of 40.0. Infrared-to-green upconversion occurs simultaneously upon excitation of the 1.5-μm emission with a commercially available 980 nm laser diode. The green-upconversion intensity has a quadratic dependence on incident pump laser power, indicating a two-photon process. Energy transfer processes and nonradiative phonon-assisted decays could account for the population of the ²H_11/2 of Er³⁺. The results indicate the possibility towards the development of lead–bismuth–gallate–germanate based glasses as photonics devices.     

High Thermoelectric Properties of PbTe Doped with Bi2Te3 and Sb2Te3

The composition-dependent thermoelectric properties of lead telluride (PbTe) doped with bismuth telluride (Bi2Te3), antimony telluride (Sb2Te3) and (BiSb)2Te3 have been studied at room temperature. All the sampies exhibit small thermal conductivity. The figures of merit, 7.63, 1.03 and 8.97 x 10-4, have been obtained in PbTe with these dopants, respectively. These values are several times higher than those of PbTe containing other dopants with small grain sizes. The high thermoelectric performance is explained by electronic topological transition induced by alloying. The results indicate that these dopants are effective to enhance the thermoelectric performance of PbTe.     

Electrical transport characteristics of ZnO–Bi2O3–B2O3 glasses

Optically clear glasses in the ZnO–Bi₂O₃–B₂O₃ (ZBBO) system were fabricated via the conventional melt-quenching technique. Dielectric constant and loss measurements carried out on ZBBO glasses unraveled nearly frequency (1 kHz–10 MHz)-independent dielectric characteristics associated with significantly low loss (D?=?0.004). However, weak temperature response was found with temperature coefficient of dielectric constant 18?±?4 ppm °C^?1 in the 35–250 °C temperature range. The conduction and relaxation phenomena were rationalized using universal AC conductivity power law and modulus formalism respectively. The activation energy for relaxation determined using imaginary parts of modulus peaks was 2.54 eV which was close to that of the DC conduction implying the involvement of similar energy barriers in both the processes. Stretched and power exponents were temperature dependent. The relaxation and conduction in these glasses were attributed to the hoping and migration of Bi³⁺ cations in their own and different local environment.     

EPR of Cu2+-doped Cs2CO3 and CsHCO3: evidence of the Jahn–Teller effect

Cu²⁺-doped Cs₂CO₃ and CsHCO₃ single crystals were investigated by electron paramagnetic resonance between 113–273 and 173–313 K, respectively. For both single crystals, two sites were observed for the Cu²⁺ at ambient temperature for arbitrary orientations of the single crystals in the magnetic field. However, when the temperature is varied, the spectra indicate the equivalence of the two sites at 225 and 240 K for the single crystals, respectively, to the above order. Below and above these temperatures two sites for Cu²⁺ appear, and below 133 and 173 K the signals do not vary and two sites were always observed. This is attributed to the transition of the dynamic Jahn–Teller effect to a static situation at lower temperatures. Cu²⁺ seems to replace Cs⁺ and the charge compensation is fulfilled by another Cs⁺. Spin-Hamiltonian parameters for both single crystals at ambient temperature are reported and discussed.