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1.
Specific properties of the hydrogen bond and protons appear to be responsible for the formation of the quasi-liquid state of conducting ions and the resulting superionic behaviour. This state is reached by successive phase transitions involving the mobile species and their interactions with a more or less rigid framework. H3OUO2PO4 · 3H2O (HUP) and CsHSO4 can be considered as models of wet and dry superionic conduction, respectively. Interactions between static effects and dynamical disorder as well as the coupling between sublattices are discussed in relation to results obtained by calorimetry, impedance spectroscopy (up to 10 GHz), vibrational spectroscopy and quasi-elastic neutron scattering. 相似文献
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Oscillation conditions of cw simultaneous dual-wavelength Nd:YAG laser for transitions 4F3/2-4I9/2 and 4F3/2-4I11/2
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The operating condition of a cw simultaneous dual-wavelength Nd:YAG laser for both {}^4F_{3/2}-{}^4I_{9/2} (quasi-three-level system) and {}^4F_{3/2}-{}^4I_{11/2}(four-level system) transitions is studied. According to this condition, the cw simultaneous dual-wavelength at 1.06μm and 946 nm in Nd:YAG crystal has been realized experimentally through an adaptive coating design of the cavity mirrors. A total power output of 2.5W of the dual-wavelength at 946nm and 1.06μm has been achieved with an optical conversion efficiency 14.3%. The experimental results are in good agreement with the theoretical analysis. 相似文献
3.
MinhuaJiang YuliaTian JianhuaJiang WanxiaHuang JiyangWang Xiao 《北京同步辐射装置》2001,(2):131-137,
Pure and neodymium-doped gadolinium calcium oxoborate crystals of high quality were grown by the Czochralski method.The orientation of crystal was precisely determined,and the samples for measurements were prepared.Through synchrotron x-ray topography and high-resolution x-ray diffractometry,the twin structure was discovered.Some properties such as the figure of merit value,and dielectric,piezoelectric,and elastic constants were meausured along with a discussion of the anisotropy of the laser properties. 相似文献
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《Solid State Ionics》1987,23(3):151-163
Premelted, predried Na2SO4, premelted Na2WO4, Na2SO4Na2WO4 composites and Na2SO4M2(SO4)3 (M = La, Dy, Sm, In) have been studied by means of X-ray diffraction, DTA and electrical conductivity measurements. The high temperature, highly conducting Na2SO4 phase I has been successfully stabilised at room temperature; the Na2SO4 containing 4 mole% La2(SO4)3 exhibits the highest conductivity (σ) and lowest activation energy (Ea) (σ=1.08 × 10−3ω−1 cm−1 at 290°C and Ea=0.50 eV) and therefore this system appears promising for further development. 相似文献
6.
Vikas S. Patil Vikas S. Padalkar Abhinav B. Tathe Vinod D. Gupta N. Sekar 《Journal of fluorescence》2013,23(5):1019-1029
Novel ESIPT inspired benzimidazole, benzoxazole and benzothiazole were synthesized from 2,4-dihydroxy benzoic acid and 1,2-phenelenediamine, 2-aminophenol, and 2-aminothiophenol respectively. The synthesized 2-(2′,4′-dihydroxyphenyl) benzimidazole, benzoxazole and benzothiazole are fluorescent and the emission characteristic are very sensitive to the micro-environment. They show a single absorption and dual emission with large Stokes shift originating from excited state intramolecular proton transfer. The absorption-emission characteristics of all these compounds are studied as a function of pH. The change in the electronic transition, energy levels, and orbital diagrams of synthesized compounds were investigated by the molecular orbital calculation and were correlated with the experimental spectral emission. Experimental absorption and emission wavelengths are in good agreement with those predicted using the Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT) [B3LYP/6-31G(d)]. Figure
Novel ESIPT inspired benzimidazole, benzoxazole and benzothiazole were synthesized from 2,4-dihydroxy benzoic acid and o- amino aromatics. Single absorption and dual emission are the interesting properties of the synthesized compounds. 相似文献
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Based on group theory and atomic and molecular reaction statics, this paper derives the possible electronic states of C^{2+}_2, C^{2-}_2 and C^{3+}_2, and their reasonable dissociation limits and determines their ground electronic states C^{2+}_2(X^3Π_u), C^{2-}_2(X^1Σ^+_g) and C^{3+}_2(X^4Σ^-_u) using quantum mechanical calculations at the level of QCISD/6-311G^*. All the potential energy curves of their ground states have both a minimum and a maximum, which are the so-called "energy trapped" molecules. This sort of potential maximum is chiefly due to Coulomb repulsion. We propose the perturbation effect of ionic charges, which is used to explain why the orbital degeneracy of diatomic ions may be removed. The characteristics of potential curves for diatomic ions are briefly described. 相似文献
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The double-doped La2/3+4x/3Sr1/3-4x/3Mn1-xMgxO3 samples with fixed Mn^3+/Mn^4+ ratio equal to 2/1 are investigated by means of magnetism and transport measurements. Phase separation is observed at temperature higher than T^onset c for x = 0.10 and 0.15. For x = 0.10, rather strong phase separation induces drastic magnetic random potential and results in the localization of carriers. Thus, the varlable-range hopping process dominates. For other samples, there is no or only weak phase separation above T^onset c. Thus, thermal activation mechanism is responsible for the high temperature transport behaviour. For x = 0.20 and 0.25, unexpected AFM behaviour is observed at low temperature. All these results are well understood by considering the special role of the "double-doping". 相似文献
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4-苯基-2-苯偶氮基-1-硫代-3, 4-二氮唑硫酮-5的谱学研究 总被引:2,自引:0,他引:2
4-苯基-2-苯偶氮基-1-硫代-3,4-二氮唑硫酮-5(C14H10N4S2)由双硫腙与二硫化碳发生加成闭环反应时获得。文章采用紫外-可见光谱的跟踪对双硫腙与二硫化碳的反应进行了系统的研究。初步讨论了反应历程,提出该反应的机理是亲核加成;并通过IR谱和NMR谱,对标题化合物的结构进行了表征。 相似文献
11.
The structures of Ga_3N, GaN_3, Ga_3N_2 and Ga_2N_3 clusters are studied using the full-potential linear-muffin-tin-orbital molecular dynamics (FP-LMTO MD) method. Four structures for Ga_3 N, five structures for GaN_3, nine structures for Ga_3N_2 and nine structures for Ga_2N_3 have been obtained. The most stable structures of these clusters are planar ones. A strong dominance of the N--N bond over the Ga--N and Ga--Ga bonds appears to control the structural skeletons, supporting the previous result obtained by Kandalam and co-workers. The most stable structures of these small GaN clusters displayed semiconductor-like properties through the calculation of the HOMO-LUMO gaps. 相似文献
12.
A blue emitting phosphor Sr3Bi(PO4)3:Eu2+ is synthesized luminescent property is investigated. Sr3Bi(PO4 )3 :Eu^2+ can by a high-temperature solid state method, and its create blue emission under the 332 radiation excitation, and the prominent luminescence in blue (423nm) due to the 4fSd^1→4f^7 transition of the Eu^2+ ion. The crystallographic sites of the Eu^2+ ion in Sr3Bi(PO4)3 are analyzed, and the 420 and 440 nm emission peaks of the Eu^2+ ion are assigned to the nine-coordination and eight-coordination, respectively. The emission intensity of Sr3Bi(PO4)3:Eu^2+ is influenced by the Eu^2+ doping content, and the concentration quenching effect is observed. The quenching mechanism is the dipole-dipole interaction, and the critical distance of energy transfer is calculated by the concentration quenching method to be approximately 1.72nm. 相似文献
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G. -S. Kim L. M. Hitchcock E. W. Rothe G. P. Reck 《Applied physics. B, Lasers and optics》1991,53(3):180-186
Some simple molecules can be excited by light within the tuning ranges of ArF (193–194 nm) and KrF (247.8–248.8 nm) excimer lasers and their fluorescence has been previously used for imaging. Additional wavelength ranges should become available by Raman shifting. As a demonstration, we present excitation and fluorescence spectra from hot O2 obtained (a) with tunable 193 nm-range light and (b) with that light shifted into the 210 nm range. All measurements are via predissociative upper states. In the 193 nm range, results are compared with those of Andresen's group. In the 210 nm range, the light is tuned to various excitation wavelengths in the (5 3), (8 4), and (7 4) bands of the B–X transition. The (7 4) excitations are well separated and the (7 v) fluoresence spectrum is in accord with Franck-Condon calculations. The wavelengths tend to overlap for the (5 3) and (8 4) excitations and the fluorescence is weaker. State-specific two-dimensional fluorescence images of an H2-O2 flame are obtained in both wavelength ranges to illustrate the use of the method.We acknowledge the National Science Foundation and the Donors of the Petroleum Research Fund, administered by the American Chemical Society, for support of this research 相似文献
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XUZhao-Xin ZHANGJun YINGHe-Ping 《理论物理通讯》2003,40(5):623-630
The ground-state and thermodynamic properties of quantum mixed-spin chains of 1/2-1/2-1-1 and 3/2-3/2-1-1 are investigated by a quantum Monte Carlo simulation with the loop-cluster algorithm. For 1/2-1/2-1-1 chain, we find it hastwo phases separated by an energy-gap vanishing point in the ground-state. For 3/2-3/2-1-1 chain,the numerical results show two energy-gap vanishing points isolated by different phases in its ground-state. Our calculations indicate that all these ground state phases can be understood by means of valence-bond-solid picture, and the thermodynamic behavior at finite temperatures is continuous as a function of parameter α=J2/J1. 相似文献
16.
First-principles study on the electronic structure and optical properties of T12Cd2(SO4)3 and Rb2Cd2(SO4)3
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With the help of ab initio full-potential linearized augmented plane wave (FPLAPW) method, calculating the electronic structure and linear optical properties is carried out for XCd2(SO4)3 (X =Tl, Rb). The results show that Tl2Cd2(SO4)3 (TlCdS) has a larger band gap than Rb2Cd2(SO4)3 (RbCdS) and the energy bands for RbCdS are more dispersive than those of TlCdS. From their partial densities of states (PDOS), we have observed that the hybridization between S ionic 2p and O atomic 2p orbitals forms SO4 ionic groups. The remarkable difference between RbCdS and TlCdS is, however, the degree of hybridization between cation (Tl and Rb) and its surrounding oxygen atoms. In the view of quantum chemistry, the strong p-d hybridization indicates the existence of their cation ionic bonds (Cd-O, Rb-O, and Tl-O). The calculations of TlCdS and RbCdS show their optical properties to be less anisotropic. Their anisotropies in the optical properties mainly occur in a low photon energy region of 5-16 eV. 相似文献
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Glass samples from two systems, Nb2O5–TeO2 and WO3–TeO2, were prepared at two melt quenching rates and characterized by density, DSC, UV-visible, and Raman spectroscopy. Addition of Nb2O5 decreased the density while increase in the WO3 concentration increased the density. Glasses prepared at higher quenching rates had smaller densities than glasses of the same composition prepared at lower quenching rate although the short-range structure of both glasses were identical, as revealed by Raman spectroscopy. Optical studies found an intense absorption band just below the absorption edge in both the glass series. This band was attributed to electronic transitions of Nb5+ and W6+ ions and a lone pair of electrons on Te atoms. Glass transition temperature increased with increase in Nb2O5 and WO3 mol% due to the increase in average bond strength in the glass network. Raman spectroscopy showed that the concentration of TeO4 units decreased with the increase in Nb2O5 and WO3 concentrations. 相似文献
18.
Seiji Sawamura Takeo Ishigami Nobuaki Egoshi Masao Tsuchiya Yoshihiro Taniguchi Keizo Suzuki 《高压研究》2013,33(6):347-353
Abstract Solubilities of seven inorganic compounds in water were measured at 298.15 K and up to 350 MPa. The solubilities of K2SO4, LiF, NaF, and KCI increased with increasing pressure, those of NH4Cl and (NH4)2SO4 decreased, and that of ZnSO4·7H2O showed almost no dependence on pressure. From the slopes of these solubility curves at 0.1 MPa, we estimated the volume changes accompanying the dissolution of the solutes. These values coincided with the volume differences between the partial molar volume at saturation and the molar volume of the crystal within ca. ± 1 cm3 mol?. 相似文献
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《Current Applied Physics》2005,5(1):43-46
The preparation and photophysics of organometallic Ir(III) complexes with 3-phenylpyridazine (H6Clppdz) and its derivative are reported. IrCl3 · nH2O reacts with H6Clppdz, and 3-chloro-6-(3′-methoxyphenyl)-4-methyl-pyridazine (MCOMppdz) to give the corresponding chloride-bridged dimers, (6Clppdz)2Ir(μ-Cl)2Ir(6Clppdz)2 and (MCOMppdz)2Ir(μ-Cl)2Ir(MCOMppdz)2 in good yields. These chloride-bridged dimers are cleaved with 2-pyrazinecarboxylic acid (Hpyzc), 2-picolinic acid (Hpic), acetylacetone (Hacac), and 2,2,6,6-tetramethyl-3,5-heptanedione (Htmd) to give the corresponding monomer, (6Clppdz)2Ir(pyzc), (6Clppdz)2Ir(pic), (6Clppdz)2Ir(acac), (6Clppdz)2Ir(tmd), (MCOMppdz)2Ir(acac), and (MCOMppdz)2Ir(tmd), respectively. The complexes show bright orange to red luminescence at room temperature and the emission wavelenghts are affected by the ancillary ligands as well as cyclometalating ligands (593–664 nm). 相似文献