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1.
Changes in the surface properties of vanadium and its alloys irradiated by Ar+ ions with the energy 20 keV, to a dose of 1022 m−2 at T irr ≈ 700K have been studied. The radiation effect consists of material surface hardening, increasing the lattice parameters of the irradiated samples, and radiation erosion of the surface layers in the form of flaking. Features of radiation damage to the material’s surface irradiated by gas ions with high sputtering coefficients are discussed.  相似文献   

2.
All-solid-state thin film batteries are feasible by employing Al as anode and LiPON as electrolyte which are subsequently deposited by sputtering. The lithium ion conductivity of ∼ 10−6 S/cm for the thin film LiPON is in agreement with data reported for bulk material. The high voltage cathode Li2CoMn3O8 could be prepared by forming the compound by the combustion method andsubsequent e-beam evaporation of this material with the addition of 20 wt.-% LiNO3 at an oxygen partial pressure of 10−5 mbar. The thin film cells could be operated between 3 and 5 V vs. Al, LiAl. The chemical diffusion coefficient was found to be in the range from 10−13 to 10−12 cm2/s at room temperature by employing the GIT-technique for the composition x of Li2-xCoMn3O8 in the range from 0.1 to 1.6. Impedance studies of the complete battery system revealed a charge transfer resistance of 290 Θ, a double layer capacity of ∼ 45–70 μF for an electrode area of 6.7 cm2 and a rate determining chemical diffusion coefficient in the range from 10−12 to 10−11 cm2/s. Paper presented at the 9th EuroConference on Ionics, Ixia, Rhodes, Greece, Sept. 15–21, 2002.  相似文献   

3.
Wu X  Guo C  Yang J  Wang M  Chen Y  Liu J 《Journal of fluorescence》2005,15(5):655-660
A new quantitative method for micro amounts of nucleic acids in aqueous solution is proposed using Eu3+-benzoylacetone (BA) complex as fluorescent probe in the presence of cetyltrimethyl-ammonium bromide (CTMAB). Under the optimum condition, the ratio of the fluorescence intensities with and without nucleic acids is proportional to the concentration of nucleic acid in the range of 1.0 × 10−9 to 5.0 × 10−6 g/mL for herring sperm DNA (hsDNA), 3.0 × 10−9 to 1.0 × 10−6 g/mL for calf thymus DNA(ctDNA) and 8.0 × 10−9 to 1.0 × 10−6 g/mL for yeast RNA (yRNA), and their detection limits are 0.33, 0.21 and 0.99 ng/mL, respectively. Actual sample (DNA of Arabidopsis thaliana) was determined satisfactorily. In addition, the interaction mechanism is also investigated.  相似文献   

4.
For a semi-infinite wide-gap crystal, expressions for the rates of one- and two-photon transitions caused by the action of linearly polarized light are obtained in the basis set of model surface and bulk functions. The transition probability is shown to significantly depend on the angle between the light polarization vector and the normal to the surface Ψ. At a light intensity of 10 MW/cm2, the probability of one-photon transitions between surface states is in the range 1024−1026 s−1 cm−2 (ψ = π/2 and ψ = 0, respectively). It is shown that, in the case wherein the light polarization vector is perpendicular to the surface, the rates of allowed n-photon transitions (n = 1, 2) decrease more slowly with increasing n than in the case in which the polarization vector lies in the plane of the surface.  相似文献   

5.
Duan’s simple model is extended to analyze the mixing of the 4f N − 15d configuration with the 4f N states. The explicit static coupling and traditional dynamic coupling are considered, and the parameters are fitted according to the absorption spectrum in LiYF4: Nd3+. The parameter values obtained are as follows: T 32 = −28i × 10−7, T 52 = −1151i × 10−7, A 322 = 192i × 10−12 cm, A 524 = i × 10−12 cm, A 726 = 54i × 10−12 cm, and A 766 = −680i × 10−12 cm. Compared to the experimental measurements, the present model yields better results than those obtained from the Judd-Ofelt theory. The text was submitted by the authors in English.  相似文献   

6.
Investigations of the sputtering of AlxGa1−x As semiconductor solid solutions by Ar+ ions with energies of 2–14 keV are performed. The dependence of the sputtering yield on the energy and angle of incidence of the ions are determined and the character of the surface relief formed during the sputtering is investigated. A comparison with theory shows that the best agreement between theory and experiment is achieved when the Haff-Switkowski formula is used together with Yudin’s stopping cross section. It is shown that the surface binding energies obtained differ from the atomization energies by an amount approximately equal to the amorphization energy. Zh. Tekh. Fiz. 67, 113–117 (June 1997)  相似文献   

7.
The thermal expansion coefficient a and structure of C60 films with thickness t∼3–10 nm were investigated in the temperature interval from room to liquid-nitrogen temperature by electron-optical methods. The thermal expansion coefficient was determined from the temperature shift of the diffraction maxima in the electron diffraction patterns. The objects of investigation were epitaxial C60 films condensed in vacuum on a (100) NaCl cleavage surface and oriented in the (111) plane. A surface-induced size effect in the thermal expansion coefficient was observed. It was established that as t decreases α f increases and is described well by the relation α f=17·10−6 K−1+8.3·10−5 nm K−1 t −1. This relation was used to estimate the linear expansion coefficient α s of the C60 surface in the (111) plane as α s=60·10−6K−1, which is several times larger than the bulk value. The experimental results agree satisfactorily with the theoretical calculations of the mean-square displacements of molecules located in a region near the surface. Zh. éksp. Teor. Fiz. 114, 1868–1875 (November 1998)  相似文献   

8.
We further discuss possible sgoldstino interpretation of the observation, reported by the HyperCP collaboration, of three Σ+pμ+μ decay events with the dimuon invariant mass 214.3 MeV within the detector resolution. With a sgoldstino mass equal to 214.3 MeV, this interpretation can be verified at existing and future B and ϕ factories. We find that the most natural values of the branching ratios of two-body B and D meson decays to sgoldstino P and vector meson V are about 10−6−10−7. The branching ratios of ϕ meson decay ϕ → Pγ are estimated to be in the range 1.8 × 10−13−1.6 × 10−7, depending on the hierarchy of supersymmetry-breaking soft terms. Similar branching ratios for ρ and ω mesons are in the range 10−14−3.4 × 10−7. The text was submitted by the authors in English.  相似文献   

9.
Sputter erosion of materials is among the most important techniques for fabricating advanced thin film coatings. Sputter processes are also of considerable relevance for surface polishing down to an atomic scale, nano-structuring of surfaces as dot and ripple patterns and micro-machining of materials using focused ion beams or reactive ion etching. We present a new, versatile sputter technique utilizing the steady state coverage of a substrate surface with up to 1016 cm−2 of foreign or self atoms simultaneously during sputter erosion by combined ion irradiation and atom deposition. These surfactant atoms (surface active agents) strongly modify the substrate sputter yield on atomic to macroscopic length scales. Depending on the surfactant–substrate combination, the novel technique allows enhanced smoothing of surfaces, the generation of novel surface patterns and nanostructures and the controlled shaping of surfaces on the nanometer scale. We present selected examples of surface morphology evolution, smoothing of surfaces and shaping of surfaces to demonstrate the capabilities of the new surfactant sputtering technique.  相似文献   

10.
Electronic surface parameters of GaAs have been determined from a qualitative and quantitative analysis of the relative photoluminescence intensity at 300 K. Characteristics of etched (100) surfaces ofn- andp-type liquid phase epitaxial GaAs have been found to be governed by negative surface charges. A density of charged surface states of about 1012 cm−2 and a band bending of 0.59 eV have been found forn-type material with an electron concentration of 1.1×1017 cm−3. Forp-type samples with hole densities ranging from 6×1015 to 4.3×1018 cm−3 the estimated density of negatively charged surface states was below 2×1011 cm−2, and the band bending was not more than a few kT.  相似文献   

11.
Thin films of molybdenum trioxide were deposited on glass substrates employing direct current (DC) magnetron sputtering by sputtering of molybdenum at different oxygen partial pressures in the range 8 × 10−5–1 × 10−3 mbar and at a substrate temperature of 473 K. The glow discharge characteristics of magnetron cathode target of molybdenum were studied. The influence of oxygen partial pressure on the structural and optical properties of molybdenum trioxide films was investigated. The films formed at an optimum oxygen partial pressure of 2 × 10−4 mbar were polycrystalline in nature with orthorhombic α- phase and an optical band gap of 3.16 eV. The refractive index of the films formed at an oxygen partial pressure of 2 × 10−4 mbar decreased from 2.08 to 1.89 with increase of wavelength from 450 to 1,000 nm, respectively. Paper presented at the Third International Conference on Ionic Devices (ICID 2006), Chennai, Tamilnadu, India, Dec. 7–9, 2006.  相似文献   

12.
We give plausible interpretations of the unusual events seen in the proton decay detector at Kolar Gold Fields indicating the existence of a massive (≳2GeV) long lived (10−8−10−9s) particle. We show that it is possible to accommodate the particle in the standard model as a fourth generation neutrino, or inE 6 grand unified theory as a neutral fermion occurring in27 representation or in supersymmetric theory as a scalar neutrino. However, there is a difficulty in explaining the large production rate for the particle.  相似文献   

13.
It was found that, if the energy released in the formation of product molecules in a heterogeneous reaction was smaller than the work function of the surface, the current density of the chemiemission of electrons from the surface of any semiconductor satisfied the condition jBexp(βE), where B and β are coefficients and E is the electric field in the semiconductor surface plane. A mathematical model describing the transfer of hot metal electrons excited in a catalytic reaction through the metal-gas interphase boundary was studied. The parameters of the system at which a study of the distribution of catalytic centers over the surface of a metal or semiconductor by the scanning tip method on the basis of the chemiemission of electrons stimulated by an electric field was possible (resolution δr ∼ 10−8–10−7 m) were determined. Theoretical results corresponded to the experimental data obtained using weak electric fields (0 < E < 5 × 106 V/m) for the heterogeneous recombination of hydrogen atoms on the surface of calcium, titanium, and n-type silicon.  相似文献   

14.
The ionic and electronic conductivities of Ag2Tl6I10 single crystals have been studied as a function of crystallographic orientation and temperature from 20 to 135°C. EMF as well as AC and DC techniques have been employed. The highly anisotropic material is predominantly an Ag+-ion conductor parallel toc-direction, with the Ag+ ions moving through linear channels that are not interconnected. The conductivity σc =1.6×10−7Ω−1cm−1 at 25°C, with an activation enthalpy for σc of 0.38 eV. The conduction perpendicular toc-direction has been found to be predominantly electronic with a value of σc =3×10−9Ω−1cm−1 at 25°C and an activation enthalpy for σc of 0.64 eV. This is the first observation of one-dimensional Ag+ conduction and this type of orientation-dependent change from ionic to electronic conduction. On leave from Institute of Physics, Academia Sinica, Peking, China.  相似文献   

15.
Thin antimony films have been epitaxially deposited at 350K onto cleavage surfaces of mica at different residual gas pressures between 10−5 and 10−9 torr, and their resistivity ∂ measured as a function of film thicknessd≦500? at temperaturesT=110K andT=300K. The ∂(d) characteristics of films deposited at residual gas pressures of about 10−6 torr with condensation rates of about 1?/s showed generally decreasing slopes as film thicknesses increased, but irregularities in detail. The ∂(d) characteristics of films deposited at 10−8 torr with the same condensation rate decreasing with increasingd, too, show no such irregularities but very small regular variations of ∂(d) with constant oscillation length Δd between the maxima, and decreasing amplitudes with increasingd. These variations are better recognizable in a modified ∂(d) graph. We tend to interprete these variations by the quantum size effect as we found oscillation lengths and amplitudes compatibel with theory.  相似文献   

16.
17.
Liquid As2Se3 undergoes the semiconductor-metal transition with increasing temperature when pressure is applied to avoid evaporation of the liquid. To investigate the atomic dynamics of liquid As2Se3, we have carried out inelastic x-ray scattering experiments of this system at 1073 K and 6 MPa and obtained the dynamic structure factor S(Q,E), from approximately 1.6 nm−1 to 11 nm−1, where Q and E are momentum and energy transfer, respectively. The excitation energy in the semiconducting state at 1073 K disperses as fast as the ultrasonic sound velocity at Q < 2.5 nm−1 but at Q > 2.9 nm−1 it disperses approximately 1.8 times faster. We analyzed S(Q,E) at 1073 K using a simple viscoelastic model and discussed Q dependence of the propagation of the acoustic mode.  相似文献   

18.
The fluorescence system of the norfloxacin-Tb3+- sodium dodecylbenzene sulfonate (SDBS) was investigated in this paper. The experiments indicated that the fluorescence intensity of the Tb3+-SDBS was greatly enhanced by the norfloxacin. On the basis of the above findings, a sensitive fluorimetric method for determining the norfloxacin was established. The fluorescence intensity was measured by a 1-cm quartz cell with the excitation wavelength of 290 nm and the emission wavelength of 545 nm. The enhanced fluorescence intensity of the system (Δ F) showed a good linear relationship with the concentration of norfloxacin in the range of 5.0×10−9 mol L−1–2.0×10−6 mol L−1, its correlation coefficient was 0.9991 and the detection limit (S/N=3) was 1.2×10−9 mol L−1. The presented method was used to determine the norfloxacin in real pharmaceutical samples. The luminescence mechanism was also discussed in detail. In the fluorescence system of the norfloxacin-Tb3+-SDBS, the SDBS not only acted as the surfactant, but also acted as the energy donor.  相似文献   

19.
A new method of stimulating secondary negative ion emission is suggested that is based on implantation of alkaline ions into the surface layer of a solid with subsequent heating to a temperature providing optimal coverage of the surface (about half a monolayer) by activator (alkaline) ions. It is shown that, by appropriately selecting the implantation dose (1018–1019 cm−3) and surface temperature (500–900°C), one can reach such a degree of coverage of the sample surface by activator ions that its work function eφ becomes minimal: 1.9 eV for molybdenum and 2.1 eV for copper. It is found that, with the implantation (irradiation) dose and surface temperature chosen properly, one can, by means of outdiffusion of cesium atoms, achieve such a degree of surface coverage that remains unchanged during the continuous sputtering of the surface by a cesium ion beam.  相似文献   

20.
The three thermo-optic coefficients of the biaxial laser host KLu(WO4)2 are measured at 633 nm by a deflection method. Their values at 300 K amount to n g / T=−7.4×10−6 K−1; n m / T=−1.6×10−6 K−1 and n p / T=−10.8×10−6 K−1. Nearly athermal propagation directions are found for polarizations along the N m and N p dielectric axes.  相似文献   

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