Single-Electron Detachment for Ti-, Fe-, Co-, Ni-, and Cu-, in Collision with Ar

By using the micro-channel plate position sensitive detector with the delay-line anode we measure the single electron detachment cross sections for some transition elements in collision with Ar in the energy region 10-30 keV. These single electron detachment cross sections perform as velocity and electron affinity dependences. The experiments are carried out using the growth rate method.     

A note on the BB, BB, DD, DD molecular states

In the framework of the one-boson-exchange model, we have performed an extensive study of the possible B*B, B*B*, D*D, D*D* molecular states with various quantum numbers after considering the S-wave and D-wave mixing. We also discuss the possible experimental research of these interesting states.     

The QKa, Branches of Carbodiimide, HNCNH, between 1.8 and 3.3 THz

The ^rQ_Ka branches of carbodiimide, HNCNH, have been recorded with a tunable far-infrared spectrometer. The ^rQ_Ka branches with K_a { 2, 3, 4 }, which occur at approximately 1.8, 2.5, and 3.2 THz, respectively, were measured rotationally resolved. The torsional doublet splitting observed in the ^rQ₀ branch and several ^rR branches by Birk et al. (J. Mol. Spectrosc.136, 402-445 (1989)) was also observed in all the Q branches reported here. In addition, anomalous K_a-type doubling was detected within the ^rQ₂ branch for rotational quantum numbers J > 18. Molecular constants were obtained by fitting the line positions, including older data, with Watson′s Hamiltonian in S-reduction. The anomalous K_a-type doubling could be described as a centrifugal distortion interaction with ΔK_a = 4. The splitting is called anomalous because it inverts the K_a = 2 energy levels of an accidentally nearly prolate symmetric top molecule (Ray′s asymmetry parameter for HNCNH κ = −0.999995343(32)).     

基于模糊PID参数自整定的细胞培养箱温度控制算法

针对细胞培养箱温度控制具有非线性、时滞性、易受干扰且难以建立精确的数学模型的特点,传统的PID控制方法对于快速维持系统箱内温度稳定存在一定的局限性。提出了以温度误差和误差变化率为控制输入,培养箱内温度为控制量的模糊PID参数自整定的温度控制算法,实现了对PID参数的实时在线修正。实验表明,该模糊PID参数自整定温度控制算法,温度从26℃上升到目标温度37℃,建立稳态的时间为2890s,温度超调极小。系统温度控制精度为±0.05℃,并在相同型号的细胞培养箱上同样得到验证。在控制稳定性方面获得了比传统PID控制更好的控温效果,稳定快,极小超调,温度控制精度高,能满足细胞培养箱温度控制的要求。     

Electronic structure of BN nanotubes with intrinsic defects NB and BN and isoelectronic substitutional impurities PN, AsN, SbN, InB, GaB, and AlB

The effect of intrinsic defects and isoelectronic substitutional impurities on the electronic structure of boron-nitride (BN) nanotubes is investigated using a linearized augmented cylindrical wave method and the local density functional and muffin-tin approximations for the electron potential. In this method, the electronic spectrum of a system is governed by a free movement of electrons in the interatomic space between cylindrical barriers and by a scattering of electrons from the atomic centers. Nanotubes with extended defects of substitution N_B of a boron atom by a nitrogen atom and, vice versa, nitrogen by boron B_N with one defect per one, two, and three unit cells are considered. It is shown that the presence of such defects significantly affects the band structure of the BN nanotubes. A defect band π(B, N) is formed in the optical gap, which reduces the width of the gap. The presence of impurities also affects the valence band: the widths of s, sp, and p_π bands change and the gap between s and sp bands is partially filled. A partial substitution of the N by P atoms leads to a decrease in the energy gap, to a separation of the Ds(P) band from the high-energy region of the s(B, N) band, as well as to the formation of the impurity Dπ(P) and Dπ*(P) bands, which form the valence-band top and conduction-band bottom in the doped system. The influence of partial substitution of N atoms by the As atom on the electronic structure of BN nanotubes is qualitatively similar to the case of phosphorus, but the optical gap becomes smaller. The optical gap of the BN tubule is virtually closed due to the effect of one Sb atom impurity per translational unit cell, in contrast to the weak indium-induced perturbation of the band structure of the BN nanotube. Introduction of the one In, Ga or Al atom per three unit cells of the (5, 5) BN nanotube results in 0.6 eV increase of the optical gap. The above effects can be detected by optical and photoelectron spectroscopy methods, as well as by measuring electrical properties of the pure and doped BN nanotubes. They can be used to design electronic devices based on BN nanotubes.     

Structural and magnetic properties of hydrides R3Fe29−xVxHy (R=Y, Ce, Nd, Sm, Gd, Tb, and Dy)

A systematic investigation of crystallographic and intrinsic magnetic properties of the hydrides R₃Fe_29−xV_xH_y (R=Y, Ce, Nd, Sm, Gd, Tb, and Dy) has been performed in this work. The lattice constants , and c and the unit cell volume of R₃Fe_29−xV_xH_y decrease with increasing rare-earth atomic number from Nd to Dy, except for Ce, reflecting the lanthanide contraction. Hydrogenation results in regular anisotropic expansions along the a-, b-, and c-axes in this series of hydrides. Abnormal crystallographic and magnetic properties of Ce₃Fe_27.5V_1.5H_6.5, like Ce₃Fe_27.5V_1.5, suggest that the Ce ion is non-triply ionized. Hydrogenation leads to the increase in both Curie temperature for all the compounds and in the saturation magnetization at 4.2 K and RT for R₃Fe_29−xV_x with R=Y, Ce, Nd, Sm, Gd, and Dy, except for Tb. Hydrogenation also leads to a decrease in the anisotropy field at 4.2 K and RT for R₃Fe_29−xV_x with R=Y, Ce, Nd, Gd, Tb, and Dy, except for Sm. The Ce₃Fe_27.5V_1.5 and Gd₃Fe_28.4V_0.6 show the larger storage of hydrogen with y=6.5 and 6.9 in these hydrides.     

Preparation and semiconductive properties of rock salt type solid solution systems,Cd1−xMxS (M = Sr, Ca, Mg, Pb, Sn)

Measurements have been made of the semiconductive properties of rock salt type solid solution systems, Cd_1?xM_xS (M = Sr, Ca, Mg, Pb, Sn) synthezised at high pressures. The Cd_1?xCa_xS system has a high electrical resistivity of more than 3 × 10¹⁰Ω-cm, and a band gap estimated from its optical absorption edge which varies from 1.9–2.6 eV with Cd_1?xPb_xS system is between 1 and 10Ω-cm, and decreases with increase in the substitution ratio. This system is photoconductive, similar to the normal pressure phase of CdS, and the photoconductivity peak shifts from 0.75–0.96μm with increase in the substitution ratio from 0.1–0.5. The above results are extrapolated to pure CdS and give for CdS having a rock salt type structure high resistivity, photoconductivity, and a band gap of 1.7–1.8 eV at room temperature and normal pressure.     

54Cr, 54, 58Fe, 58Ni(d,p)55Cr, 55, 59Fe, 59Ni Vector analyzing power measurements

(d, p) cross sections and vector analyzing powers have been measured at 10 MeV bombarding energy for targets ⁵⁴Cr, ⁵⁴Fe, ⁵⁸Fe and ⁵⁸Ni. The systematic behaviour of the analyzing powers with Q for states of a given J^π has been observed. Spins of a number of states in ⁵⁵Cr and ⁵⁹Fe have been deduced.     

Study of the structural stability of LnNbxOy systems (Ln = La, Ce, Pr, Nd, Pm, Sm, Eu) by the Xα method of discrete variation

The electronic structure and Ln-O (Ln = La, Ce, Pr, Nd, Pm, Sm, Eu) bonding parameters have been calculated by the X _α method of discrete variation taking into account the real structure of LaNb₇O₁₂ oxoniobate. It is shown that the experimentally observed tendencies in the change in the oxoniobate stability correlate with the decrease in the average electron-proton binding energy of LnO₈ clusters and enhanced repulsion between Ln and O orbitals to the end of the lanthanide series. Original Russian Text ? E.I. Yurieva, O.G. Reznitskikh, V.G. Bamburov, 2009, published in Izvestiya Rossiiskoi Akademii Nauk. Seriya Fizicheskaya, 2009, Vol. 73, No. 7, pp. 1066–1068.     

Optoelectronic properties of LixAxNbO3 (A=Na, K, Rb, Cs, Fr) crystals

The structural and optoelectronic properties of Li_xA_xNbO₃ (A=Na, K, Rb, Cs, Fr and x=0, 0.5) compounds have been investigated by the generalized gradient approximation within density functional theory. The calculated fundamental direct band gap of pure LiNbO₃ is 3.32 eV. It is found that the substitution of alkali elements drastically change the optoelectronic nature of the compound from direct to indirect bandgap semiconductor and the fundamental gap also decreases. The nature of the compound is ionic with strong bonds between alkali ions and O, while there are partial covalent bonds between Nb and O. The calculated static refractive index of pure LiNbO₃ is 2.43 for the perpendicular plane to the c-axis, while 2.37 for the parallel plane to the c-axis. So these values are intensively dependent on the substitution of alkali metals. The calculated electron energy loss spectra are in good agreement with the experimental results. It also predicts some extra interesting peaks, which have not been observed in experiments.     

Rotational Spectra of cis-HCOOH, trans-HCOOH, and trans-HCOOH

While the rotational spectrum of trans-HCOOH is well known, the cis-rotamer was known previously only from a few microwave transitions. The spectra of cis- and trans-HCOOH and of trans-H¹³COOH have been identified in the far infrared Fourier transform spectrum recorded in the range 20-100 cm⁻¹. The measurements were performed using an 80-cm base length White-type multipass absorption cell in combination with a Bruker IFS 120 HR spectrometer. The White cell was set up for 90 passes (total path length=72 m) and the spectrum was measured with a resolution (FWHM) of 0.0012 cm⁻¹. Submillimeter-wave transitions, just under 1 terahertz, of the same three species of formic acid were measured in the range from 835 to 993 GHz (27.8-33.1 cm⁻¹) and it was possible to assign b-type Q-branch transitions of both cis- and trans-HCOOH in this region, and also transitions of trans-H¹³COOH. These measurements served furthermore as a check on the calibration of the FTIR measurement. Furthermore, new millimeter-wave measurements in the range 172-366 GHz were made, bridging the gap between the MW and FIR lines for cis-HCOOH and providing important data for trans-H¹³COOH. The assigned FTIR, submillimeter- and millimeter-wave data reported in this work were fitted together with previously published rotational transitions to obtain rotational constants, using Watson's A-reduced Hamiltonian, for cis-HCOOH, trans-HCOOH, and trans-H¹³COOH.     

Single-neutron transfer reactions 76, 78, 80, 82Se(p,d)75, 77, 79, 81Se at EP = 33MeV

Single-neutron transfer reactions on even-even Se nuclei have been studied using 33 MeV incident proton energy from the ANU cyclograaff facility. A total of 120 levels have been seen below 4 MeV excitation energy in ^{75, 77, 79, 81}Se isotopes. Angular distributions for 88 states were extracted and analysed with DWBA theory yielding a number of new l_n assignments. Coriolis coupling calculations have been carried out for low-level spin states in all four isotopes.     

铁基Heusler合金Fe2Co1-xCrxSi的结构、磁性和输运性质的研究

基于多种实验手段和能带计算的方法, 对四元合金Fe₂Co_1-xCr_xSi的晶体结构、 磁性、输运性质及能带结构进行了研究. 研究发现, 随着Cr的增加, 合金Fe₂Co_1-xCr_xSi保持了高度有序结构, 逐渐从Hg₂CuTi结构的Fe₂CoSi 过渡到L2₁结构的Fe₂CrSi; 由于次晶格网络的破坏, 居里温度逐渐下降; 系列合金的分子磁矩呈现线性下降, 符合半金属特性; 剩余电阻比率与原子占位有序程度密切相关, 呈现两端大、 中间小的特点. 在Cr替代Co的过程中, 材料半金属能隙逐渐打开, 表现半金属特征. 同时费米能级从Fe₂CoSi半金属能隙的价带顶上移至Fe₂CrSi能隙的导带底. 最大的能隙宽度出现在x= 0.75处, 这表明四元合金有可能成为具有更高自旋极化率和更强抗干扰能力的自旋电子学材料.     

Relation between electrooptical constants and polar tensors of CH3F,CD3F,CH3Cl,CD3Cl,CH3Br,CD3Br,CD3I,and CD3I

Infrared intensity analysis was done in two ways. In one approach, formulas connecting electrooptical parameters (eop's) and intensities were derived and, using the intensities, the former were obtained. In evaluating the eop's the intensity sum equations were used directly so that the sign ambiguity of $\text{δP}\text{δQ}$ is avoided. In the other method, polar tensors were obtained directly from intensities. The two methods have now been connected, and polar tensors have been obtained in terms of electrooptical parameters so that the former were also free from sign ambiguity of $\text{δP}\text{δQ}$. They compare well with those obtained directly from intensities. In similar connecting formulas by other authors [see, for example, P. L. Prasad, J. Chem. Phys., 69, 4403, (1978)], both polar tensors and eop's were affected by the sign ambiguity.     

Some crystallography,chemistry, physics,and thermodynamics of B12O2, B12P2, B12As2, and related alpha-boron type crystals

This paper shows that several alpha-boron type compounds may be useful as high-temperature semiconductors with decent carrier motilities, high electrical resistivity, good optical transparency, good stability under high radiation bombardment, and possess high neutron capture cross-sections. The most promising are B₁₂O₂, B₁₂P₂, and B₁₂As₂. Their relationship to alpha-boron, B₁₃C₂, and other derivative crystals is explained. A study of their chemical and thermodynamic properties indicates how single crystals useful for electronic devices can be grown.     

Magnetic properties of RPd5Al2 (R=Y, Ce, Pr, Nd, Sm, Gd)

Polycrystalline samples of a new rare-earth series RPd₅Al₂ crystallizing in the tetragonal ZrNi₂Al₅-type structure have been prepared. Their physical properties by electrical resistivity ρ, magnetic susceptibility χ, magnetization M and specific heat C_p measurements are reported. The ingots are composed of elongated grains preferentially aligned in the c direction; therefore, measurements were conducted parallel and perpendicular to the grains. Antiferromagnetic ordering appears in R=Ce, Nd, Gd, and Sm at low temperatures. CePd₅Al₂ has two AFM transitions at 4.1 and 2.9 K and ρ(T) indicates a Kondo metal behavior with large anisotropy. In PrPd₅Al₂ no magnetic transition was observed down to 0.4 K. The C_p(T) shows a broad peak around 13 K due to the CEF effect, suggesting a non-magnetic singlet ground state. In NdPd₅Al₂, χ(T) shows anisotropy and the C_p(T) shows a sharp peak at 1.2 K. The magnetic entropy at 3 K is very close to Rln2, indicating a Kramers doublet ground state. In SmPd₅Al₂, C_p(T) shows a magnetic transition at 1.7 K. C_p(T) for GdPd₅Al₂ shows a peak at 6 K, followed by a broad anomaly around 3 K. Within this series, T_N's for CePd₅Al₂ and NdPd₅Al₂ clearly deviate from the relation predicted by de Gennes scaling, which is ascribed to the CEF effect.     

H1+,H2+,H3+和He,Ne,Ar碰撞过程中的巴耳末系Hα,Hβ,Hγ发射

实验利用TN-1710光学多道分析系统(OMA),对H₁⁺,H₂⁺,H₃⁺和He,Ne,Ar碰撞过程中产生的巴耳末系H_α,H_β,H_γ发射进行了测量,入射离子H₁⁺,H₂⁺,H₃⁺的 关键词：     

Spectra and multiplicities of n, p, d, t, K, π from antiproton annihilation in Cu and U

Inclusive energy spectra of neutrons, protons, deuterons, tritons, charged kaons and pions following antiproton annihilation at rest in copper and uranium have been measured. The determined multiplicity charged kaons is compared to recent measurements and indicates an enhancement of strangeness production. Ratios of directly emitted neutrons and protons have been determined for copper and uranium to 3.0±0.6 and 3.2±0.5, respectively.