The electronic structure of α-cerium from magnetization data

The magnetic properties of α-cerium are determined. It is shown that an analysis in terms of the Stoner model and a Lorentzian 4?-peak in the density of states can be made consistent in a two-band model, but not in a single-band model.     

用高斯分布法计算非晶态聚合物聚氯乙烯主转变过程中的动态力学弛豫时间谱分布

对非晶态聚合物聚氯乙烯PVC进行不同频率升温扫描的动态力学弛豫谱测量,发现主转变内耗峰(α峰)峰形及其他峰参数均随频率变化。本文根据连续分布谱的理论讨论PVC主转变内耗峰弛豫时间τ的分布情况,并通过高斯分布时方法,计算出PVC主转变弛豫过程中弛豫时间常数τ₀和激活能△H对弛豫时间τ的贡献权重。指出τ₀和△H在PVC主转变过程中都有明显的分布。     

The effect of reactor irradiation on the dielectric loss peaks of Nylon and Mylar

The effect of irradiation on the dielectric properties of nylon 66.6 and Mylar was studied. In the case of nylon the dielectric loss peak at 350 K measured with an annular frequency of 10⁴ l/s disappeared due to irradiation and the peak at higher temperaturcs shifted to still higher temperatures. In Mylar the α-peak grew in magnitude, indicating an increase in amorphousness, while the β-peak decreased. A rough estimate for the decrease in the magnitude of the effective number of dipoles is presented. The irradiation was carried out up to fast neutron fluence of 3 × 10¹⁷ nvt and gamma dose of 1 × 10⁹ rad.     

Preparation, characterization and thermally stimulated luminescence of ZnO nanophosphor

Pure nanocrystalline ZnO thermoluminescent phosphor was synthesized by chemical co-precipitation method. The prepared sample was characterized by XRD, SEM and FTIR. The powder samples when exposed to X-irradiation showed that the thermoluminescence response increases linearly with the increase of the time of X-irradiation. The glow curve exhibited two maxima centered at 116 and 207°C. The latter glow peak displays greater stability and sensitivity when the phosphor is exposed to X-irradiation at room temperature. The results indicate that this new ZnO phosphor is a promising detector and dosimeter for X-irradiation.     

高密度激发下CdS中束缚激子与激子的散射发光

本文在液氦温度下在CdS中观测到一个新的发光峰,并提出束缚激子与激子非弹性散射发光模型对该峰的产生和特性进行了解释。     

电子倍增CCD的电荷倍增特性研究

建立了电子倍增CCD的载流子倍增寄存器的电荷倍增模型,分析了电子倍增CCD的结构特征和载流子倍增寄存器的工作原理及其电荷倍增特性.利用Z域分析方法得到载流子倍增寄存器的电荷倍增传递函数及其幅频响应.计算表明,提高载流子倍增寄存器的电荷倍增系数可以提高电子倍增CCD的幅频响应.同时,用增益起伏因子来分析载流子倍增寄存器的增益起伏特性,得到了电荷倍增率,寄存器级数与增益起伏因子的数值关系.在寄存器级数N=400条件下,当电荷倍增系数α≤0.15时,增益起伏因子随电荷倍增系数增大而增大;而当α≥0.15时,增益起伏因子随电荷倍增系数的增大而减小.通过典型的电子倍增CCD相机的实验验证了建立的模型.     

Thermoluminescence and thermally stimulated currents in PbMoO4 crystals

Thermally stimulated depolarization (TSD) currents have been studied in the range from 4 K to room temperature by utilizing direct contacts as well as blocking contacts. Charge carrier injection and subsequent trapping seem to be responsible for internal electric fields. A glow peak near 186 K arises from a dipolar relaxation. The results of additional optical excitation during polarization provide some more information on charge transport involved in relaxation processes. The correlation to the results of photoconductivity and annealing procedure leads to the assumption of oxygen vacancies as the dominant defect centres. The study of thermoluminescence (TL) after X-irradiation gives evidence on defect states in question. In addition, from the results quasi-free charge carriers are assumed to be thermally generated above 100 K.     

Dielectric relaxation investigations of 100 MeV Ag-ion-irradiated polyetherimide using thermally stimulated discharge current techniques

The thermally stimulated discharge current technique (TSDC) has been used to elucidate various dielectric relaxation processes in 100 MeV Ag-ion-irradiated polyetherimide (PEI). The irradiated PEI samples (85 μm thickness, area 0.12 cm²) were polarized at different temperatures ranging from 50–200 °C under various biasing fields (50–300 kV/cm). TSDC spectra, in general, consist of four current maxima namely γ, β, α and ρ in ascending order of temperature, appearing around 40, 110, 200 and 230 °C, respectively. The origin of γ - and β -peaks has been attributed to the dipolar nature of ether linkages and carbonyl groups, respectively, whereas α- and ρ-maxima have been attributed to the space charge polarization process. The absence of γ-peak in irradiated samples is attributed to the significant loss in ether linkages due to irradiation. The free radical formation, demerization of carbonyl groups and cross-linking of imide groups due to ion irradiation in PEI have been held to be responsible for the behavior of these relaxation processes. In the vicinity of the β-relaxation, a new relaxation process, termed δ-relaxation, is also observed.     

核军控核查符合测量系统中去除γ射线新方法

为消除γ射线的影响,在阐述核军控核查技术中的符合测量方法原理的基础上,分析了γ射线对于符合测量系统性能的影响机理,提出了一种新的去除γ射线峰的方法——拒绝窗口法.通过实验验证,利用该方法可以显著降低γ射线峰对符合测量系统性能的影响,且对子射线的去除率达到了99％,大大改善了核武器识别系统的测量效果.     

Investigation of electronic and ionic transport properties in α-MoO3 cathode material by electrochemical impedance spectroscopy

Electrochemical impedance spectra (EIS) for lithium ion insertion and extraction in α-MoO₃ cathode material were obtained at different potentials during initial discharge–charge cycle. A significant “three semicircles” were obtained at 0.5 V in the Nyquist diagram, and were assigned to lithium ion migration through solid electrolyte interphase (SEI) film, the electronic properties of the material as well as charge transfer step, respectively. An equivalent circuit that includes elements related to the electronic and ionic transport, in addition to the charge transfer process, is proposed to simulate the experimental EIS data. The variations of the resistance of SEI film, the electronic conductivity of the material and the resistance of charge transfer along with the increase and decrease of electrode polarization potential were quantitatively analyzed, and the reasonable explanation is given. Furthermore, the chemical diffusion coefficients of lithium ion in α-MoO₃ cathode material were calculated.     

Silver atom center in α-quartz

A new paramagnetic center, Afs_Ag?Si, in silver-diffused α-quartz is described and its spin-Hamiltonian parameters are presented. The center is formulated as a silver atom $\text{(S =}\text{1}\text{2}\text{)}$ situated in a c-axis channel, bonded weakly to a normal silicon cation, with four oxygen anions as neighbors. A_Ag?Si is created by X-irradiation and is unstable at room temperature.     

Unusually large shift in low-temperature susceptibility peak of Fe2.8Ti0.2O4 with frequency

The temperature dependence of magnetic susceptibility,x, of titanomagnetites (Fe_3−x Ti _x O₄, 0⩽x⩽0.2) at different frequencies in the range of 13 Hz to 117 kHz is reported. Whereas the position of thex-peak of Fe₃O₄ at 120 K shows no significant shift over this frequency range, that of Fe_2.8Ti_0.2O₄ shifts from 70 K at 13 Hz to 115 K at 117 kHz. This seems to be the first observation of such large shift in the position of ax-peak observed at low-temperatures is attributed to the occurrence of an isotropic point (temperature at which first order anisotropy constantK ₁=0) associated with change in crystal structure. In such a case a shift inx-peak with frequency is not expected normally. Thus, the observed large shift in the position ofx-peak with frequency is an unusual phenomenon and some of its repercussions are discussed.     

Mg-Zr合金微观组织电子结构研究

用递归法计算了α-Mg与α-Zr的结构能、原子结合能,Mg/Zr界面能与Mg的表面能,Mg中Zr及Zr中Fe,Mn,Si,H等杂质原子相互作用能,Mg,Zr原子态密度及其在合金中的电荷变化. 计算发现,在晶体中与Mg态密度差别很大的Zr在Mg/Zr界面却与Mg趋于相近,从而界面电子环境与Mg相似,为Mg形核生长提供有利条件;α-Zr的结构能、原子结合能低于相应的α-Mg,且Mg/Zr界面能低于Mg的表面能,从能量角度合理解释了Zr先于Mg从Mg熔体析出,并作为异质核心细化Mg晶粒的实验现象. 原子相互作用 关键词： 电子结构 晶粒细化 Mg合金     

Thermally and optically stimulated radiative processes in LiBaF3 crystals

In LiBaF₃ crystals both valence–core transitions (5.4–6.5 eV) and so-called self-trapped exciton luminescence (about 4.3 eV) are important for practical application. Here, we present a study of 4.3 eV luminescence under photo- and thermostimulation after X-irradiation of undoped LiBaF₃ crystals at various temperatures. Optically stimulated luminescence as a result of electron recombination with both self-trapped holes and holes localized at some defects, were observed after X-irradiation below 130 K and that of electron recombination with defect-localized holes was observed after X-irradiation above 130 K. The spectra of thermo-stimulated luminescence (TSL) contain a broad band about 4 eV related to the electron (high-energy side) or hole (low-energy side) recombination depending on TSL peak temperature.     

COVARIANT AND QUANTIZATION OF SPINNING STRING IN Md×G SPACE-TIME

The BRS charge Q_B of BRSSS Spinning String model in M_d×G space-time is explicitly given.By means of the nilpotency of the BRS charge,the critical dimension and parameters α^R and α^NS could be fixed;and with the help of the BRS charge a BRS invariant free open BRSSS string field theory could be established.In this model,we find that supersymmetry and BRS invariance could be compatible only when the group G is abelian.And finally,the massless sector comprising gauge fields with indices of group G is demonstrated.     

The Role of Normal Versus Twisted Intramolecular Charge Transfer Fluorescence in Predicting the Forms of Inclusion Complexes of Ethyl-4-dialkylaminobenzoate with α-Cyclodextrin in Aqueous Solution

An evidence is introduced through the b- and the twisted intramolecular charge transfer (TICT) fluorescence of ethyl-4-(N,N-dimethylamino)benzoate (EDMAB) and ethyl-4-(N,N-diethylamino)benzoate (EDEAB), confirming the role of donor size on the formation and emission of various inclusion complexes formed between these probes and α-CD in aqueous solution. A large variation in the b-fluorescence band of EDEAB as compared to that of EDMAB and a large variation in the TICT-fluorescence band of EDMAB as compared to that EDEAB, as the concentration of α-CD is increased in their aqueous solutions are observed. These variations are supported by time resolved fluorescence (TRF) spectra, fluorescence decay lifetimes and red edge effect (REE) results.     

Optical and ESR studies in pure and Mn-doped LiF crystals

Growth of F absorption band with the time of X-irradiation at RT and the changes caused in the F absorption as a function of F light and thermal bleaching along with the simultaneous ESR studies in pure and Mn-doped LiF single crystals are reported.     

Single- and double-electron charge transfer in collisions of α-particles with hydrogen molecules

Total, partial, and angular differential cross sections of single- and double-electron charge transfer in collisions between α-particles and hydrogen molecules in the ground state in the interval of collision energies from 3 to 80 keV have been calculated. New data for charge transfer cross sections can be used for simulations and spectroscopy of α-particles in thermonuclear diverter plasma of nuclear reactors.     

Extraction of Surface Roughness from the Central δ-peak of Light Scattering Using a Multi-wavelength Ar+ Laser

In this paper, a new light scattering method for measuring the roughness of random surfaces is proposed. The method is based on the relation between the specularly reflected intensity Is, i.e., the central δ-peak intensity and wave vector component kz. The linear fit of the logarithm graph of the normalized central δ-peak intensity Isr versus k2z, whose variation is induced by changing illuminating wavelength, gives the square of the surface roughness w. The roughnesses of 6 silicon backside samples were measured.     

Extraction of Surface Roughness from the Central δ-peak of Light Scattering Using a Multi-wavelength Ar~ Laser

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