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1.
《光谱学与光谱分析》2016,(12):4125-4129
K shell fluorescence parameters of pure Ti and some of its compounds have been determined experi-mentally using an Ultra-LEGe detector with resolution 150 eV at 5.9 keV.The samples were excited 5.96 keV photons emitted from a 55 Fe radioisotope source with 50 mCi activity.The experimental values of the K shell fluorescence parameters have been compared with the experimental and theoretical values available in the litera-ture for pure Ti.  相似文献   

2.
The critical currents of YBa2Cu3O7-x thin films have been measured at 74. 3K in magnetic fields up to 2.1T and at the temperature range from 64K to Tc in the absence of the field. Jc-B and Jc-T data were fitted to the flux creep model. The values of pinning energy and number density of pinning centers were obtained from the fits. The results show that the measured critical current density is flux-creep-limited and is several times smaller than Jco, the critical current density in the absence of flux creep. The distribution of pinning energies and inhomogeneity may be responsible for the discrepancy of pinning energy values obtained from different methods.  相似文献   

3.
The measurement of K shell fluorescence parameters is an easy and practical way to investigate the electronic structures of elements in alloys,compounds or complexes.Since the number of valence electrons will change the screening effect,the measured parameters will be affected from the changes.In this study,the measured parameters were investigated for sulphur element according to the number of CH_2 groups.For the experimental measurements,the samples were excited by 59.5keVγrays from a 241 Am annular radioactive source.The emitted K X-rays from the samples were counted by ab Ultra-LEGe detector with a resolution of 150 eV at 5.9keV.  相似文献   

4.
The photoneutron reaction18Ta(y,3m)(178m,g)Ta was investigated with the beam from the NSC KIPT electron linear accelerator LUE-40.The measurements were performed using the residual y-activity method.The bremsstrahlung flux-averaged cross sections((Eγmax)>.(r(Eγmax)>m.γmax)g and the isomerie ratio of the re-action products d(Eγmax)were measured.The theoretical values of the averaged cross-sections and isomeric ratio were calculated using the partial cross-sections from the TALYS1.95 code for different level density models LD 1-6..The obtained experimental d(Eγmax)agree with the data in the lterature,but differ from the theoretical values in ab-solute magnitude and the behavior of the energy dependence.A comparison of the determined averaged cross-sec-tions with the calculated cross sections showed the best agreement for the case of the LD 5 model.  相似文献   

5.
A systematics of excitation energy of the first 2^+ state E2+ in even-even heavy nuclei (A ≥ 120) is studied in the NpNn scheme. It is found that a simple exponential function describes the dependence of E2+ values on NpNn values very well. In addition, the Z = 64 shell gap is reexamined by investigating the systematics of the 52 ≤ Z ≤66 region. It is found that the Z = 64 shell gap is largest at N = 82 and becomes smMler with either increasing or decreasing of neutron numbers. The effects of this shell gap become negligible for counting the valence proton numbers when N ≥ 92 or N ≤ 72.  相似文献   

6.
The viscosities, η, and ultrasonic speeds, u, of pure benzene, triethylamine, (TEA) tributylamine, (TBA), and those of their binary mixtures, with benzene as common component, covering the whole composition range have been measured at 278.15 K, 283.15 K, 288.15 K, 293.15 K, 298.15 K, 303.15 K, 308.15 K, 313.15 K, and 318.15 K. From the experimental data the deviations in viscosity, △η, deviations in Gibbs free energy, AG, deviations in ultrasonic speed, △u, deviations in entropies, △S^*, and deviations in enthalpies, △H^*, of activation of viscous flow have been determined. The sign and magnitude of these parameters were found to be sensitive towards interactions prevailing in the studied systems. Further, the excess molar volumes, VE, were calculated using data for the binary mixtures. Moreover, theoretical values of viscosities and ultrasonic speeds of the binary mixtures were calculated using different empirical relations and theories. The results were in experimental and theoretical values. discussed in terms of average deviations (AD)  相似文献   

7.
The effects of F^- ions in a germanium-lead-tellurite glass system on the spectral and potential laser properties of the Yb^3 are investigated. The absorption spectra, lifetimes, the emission cross-sections and the minimum pump intensities of the glass system with and without F^- ions have been measured and calculated. The results show that the fluorescence lifetime and the minimum pump intensity of Yb^3 ions increase evidently, which indicatesthat germanium-lead-oxyfluoride tellurite glass is a promising laser host matrix for high power generation. FT-IRspectra were used to analyse the effect of F^- ions on OH^- groups in this glass system. Analysis demonstrates that addition of fluoride removes the OH^- groups and results in improvement of fluorescence lifetime of Yb^3 .  相似文献   

8.
In this work, based on the liquid-drop model and considering the shell correction, we propose a simple formula to calculate the released energy of proton radioactivity(Q_p). The parameters of this formula are obtained by fitting the experimental data of 29 nuclei with proton radioactivity from ground state. The standard deviation between the theoretical values and experimental ones is only 0.157 Me V. In addition, we extend this formula to calculate 51 proton radioactivity candidates in region 51≤Z≤83 taken from the latest evaluated atomic mass table AME2016 and compared with the Q_p calculated by WS4 and HFB-29. The calculated results indicate that the evaluation ability of this formula for Q_p is inferior to WS4 while better than HFB-29.  相似文献   

9.
肖星星  谢文杰  唐新峰  张清杰 《中国物理 B》2011,20(8):87201-087201
With good electrical properties and an inherently complex crystal structure,Cu 2 x Se is a potential "phonon glass electron crystal" thermoelectric material that has previously not attracted much interest.In this study,Cu 2 x Se (0 ≤ x ≤ 0.25) compounds were synthesized by a melting-quenching method,and then sintered by spark plasma sintering to obtain bulk material.The effect of Cu content on the phase transition and thermoelectric properties of Cu 2 x Se were investigated in the temperature range of 300 K-750 K.The results of X-ray diffraction at room temperature show that Cu 2 x Se compounds possess a cubic structure with a space group of F m3m (#225) when 0.15 < x ≤ 0.25,whereas they adopt a composite of monoclinic and cubic phases when 0 ≤ x ≤ 0.15.The thermoelectric property measurements show that with increasing Cu content,the electrical conductivity decreases,the Seebeck coefficient increases and the thermal conductivity decreases.Due to the relatively good power factor and low thermal conductivity,the nearly stoichiometric Cu 2 Se compound achieves the highest ZT of 0.38 at 750 K.It is expected that the thermoelectric performance can be further optimized by doping appropriate elements and/or via a nanostructuring approach.  相似文献   

10.
To study the screening effect of nuclear reactions in metallic environments, the thick target yields, the cross sections and the experimental S(E) factors of the D(d,p)T reaction have been measured on deuterons implanted in Sm metal at 133.2K for beam energies ranging from 10 to 20keV. The thick target yields of protons emitted in the D(d,p) T reaction are measured and compared with those data extrapolated from cross sections and stopping power data at higher energies. The screening potential in Sm metal at 133.2K is deduced tobe 520±56eV. As compared with the value achieved in the gas target, thecalculated screening potential values are much larger. This screening potential cannot be simply interpreted only by the electron screening. Energy dependences of the cross section σ(E) and the experimental S(E) factor for D(d,p)T reaction in Sm metal at 133.2K are obtained, respectively.  相似文献   

11.
Nuclear level densities of 47V, 48V, 49V, 53Mn, 54Mn, 57Co, 59Ni and their energy dependences are determined from measurements of the neutron evaporation spectra in the (p, n) reaction. Neutron spectra from the (p, n) reaction on nuclei of 47Ti, 48Ti, 49Ti, 53Cr, 54Cr, 57Fe, and 59Co are measured at proton energies between 7 and 11 MeV. The data are analyzed in terms of statistical equilibrium and pre-equilibrium models of nuclear reactions.  相似文献   

12.
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14.
采用紧束缚的分子动力学模型,对Nan(5≤n≤10)小团簇的键长涨落、势能、热容量等熔化性质在50 K~1500 K温区进行了模拟研究,结果表明:它们发生两次相变,一种在230 K~300 K的温度范围内,依次有块体玻璃态转变;一种在550 K~870 K温度段,依次经历了熔化相变.同时也得到随着团簇体系的减小,势能由下向上排列的曲线,即体系的势能由低变高.  相似文献   

15.
Photoemission spectra for gold have been measured for photon energies 15≤hv≤90 eV using synchrotron radiation. We observe the transition from the ‘band structure’ regime (hv?30 eV) where spectra are strongly modulated by matrix elements to the high energy regim (hv?30 eV) where spectra reflect structure in the single-particle density of states.  相似文献   

16.
彭文屹  覃金  章爱生  严明明 《物理学报》2010,59(11):8244-8248
采用X射线衍射分析、显微形貌观察、差示扫描量热法、标准电阻应变计法等实验方法,研究了室温下多晶Mn1-xCux(0.1≤x≤0.3,原子分数)合金在低磁场中的磁诱发应变性能.结果表明,Mn1-xCux合金经过长时间的固溶处理,在冷却过程中会出现fcc(γ)→fct(γ’)马氏体相变,形成(γ+γ 关键词: 磁诱发应变 MnCu合金 马氏体相变  相似文献   

17.
The reaction pppπ+ X was studied at different incident energies around T p = 2 GeV. Narrow baryonic structures were observed in the missing mass M X and in the invariant mass M pπ{+}. The masses of these structures are 1004, 1044, 1094, 1136, 1173, 1249, 1277, and 1384 MeV (and possibly 1339 MeV). Some of them were also observed at the same masses in the missing-mass spectra of the dp → ppX reaction although with a weaker signature. Many checks were performed to make sure that these structures were not produced by experimental artifacts. Several narrow small-amplitude peaks, were also extracted using already published photonucleon cross-sections. The small widths of all these results, and the stability of the observed structures, regardless of the experiment, were used to conclude that they are genuine baryons and not merely the consequence of dynamical rescatterings. These baryons cannot be associated with classical q3 quark configurations. We associate them with two colored-quark cluster configurations. Received: 3 July 2002 / Accepted: 30 January 2003 / Published online: 5 June 2003  相似文献   

18.
The half-lives of deformed nuclei are reported for 67≤Z≤91. We consider an angle-dependent potential which yields multiple approximations. The results are in better agreement with the experimental data when the multiple approximation is solely considered for the daughter nuclei.  相似文献   

19.
Luminescent materials composed of Sr3?x?3y/2MxCeyAlO4F (M=Ca, Ba, 0≤x≤0.9, 0.001≤y≤0.05) were prepared by the solid-state reaction method. X-ray diffraction (XRD) patterns of the obtained oxyfluorides are exhibited for indexing peak positions. Dynamic excitation and emission spectra of the Ce3+-activated oxyfluoride phosphors are clearly monitored. The critical emission quenching as a function of Ce3+ contents in Sr2.5?3y/2M0.5CeyAlO4F phosphors is revealed at quite low concentrations of the activator. CIE coordinates of blue and green Sr2.5?3y/2M0.5CeyAlO4F phosphors are clearly measured. The relative quantum efficiency of Sr2.4985Ca0.5Ce0.005AlO4F based on the integrated emission is determined. The Sr3?x?3y/2MxCeyAlO4F phosphors excited near 410 nm light could be prominent phosphors in applications of NUV-LED.  相似文献   

20.
We report on the vibrational properties of spinel LiMn2O4 and its electrochemically delithiated forms LixMn2O4. Raman scattering and infrared absorption spectra have been studied as a function of the delithiation content in the wavenumber range 50–700 cm−1. Results show that lithium ions can be extracted at room temperature to obtain Lix[Mn2]O4 (0.3≤x≤1.0) without disrupting the [Mn2]O4 array. The normal modes of the spinel LiMn2O4 have been discussed in the O h 7 symmetry and vibrations due to lithium ions with their oxygen neighbors have been identified at ca. 400 cm−1. Paper presented at the 3rd Euroconference on Solid State Ionics, Teulada, Sardinia, Italy, Sept. 15–22, 1996  相似文献   

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