Demonstration of Inverse Scattering Transform for DNLS Equation

Since the Jost solutions of the DNLS equation does not tend to the free Jost solutioins as |λ| →∞, the usual inverse scattering transform (IST) must be revised. Beside the Kaup and Newell's approach, we propose a simple revision in constructing the equations of IST, where the usual Zakharov-Shabat kern is revised by multiplying λ-2 or λ-1. To justify the revision we show that the Jost solutions obtained do satisfy the pair of compatibility equations.     

Inverse Scattering Transform in Squared Spectral Parameter for DNLS Equation under Vanishing Boundary Conditions

After a transformation, the inverse scattering transform for the derivative nonlinear Schr6dinger （DNLS） equation is developed in terms of squared spectral parameter. Following this approach, we obtain the orthogonality and completeness relations of free Jost solutions, which is impossibly constructed with usual spectral parameter in the previous works. With the help these relations, the Zakharov-Shabat equations as well as Marchenko equations of IST are derived in the standard way.     

Improved device performance of recessed-gate AlGaN/GaN HEMTs by using in-situ N2O radical treatment

The N₂O radicals in-situ treatment on gate region has been employed to improve device performance of recessed-gate AlGaN/GaN high-electron-mobility transistors (HEMTs). The samples after gate recess etching were treated by N₂O radicals without physical bombardment. After in-situ treatment (IST) processing, the gate leakage currents decreased by more than one order of magnitude compared to the sample without IST. The fabricated HEMTs with the IST process show a low reverse gate current of 10^-9 A/mm, high on/off current ratio of 10⁸, and high f_T×L_g of 13.44 GHz· μm. A transmission electron microscope (TEM) imaging illustrates an oxide layer with a thickness of 1.8 nm exists at the AlGaN surface. X-ray photoelectron spectroscopy (XPS) measurement shows that the content of the Al-O and Ga-O bonds elevated after IST, indicating that the Al-N and Ga-N bonds on the AlGaN surface were broken and meanwhile the Al-O and Ga-O bonds formed. The oxide formed by a chemical reaction between radicals and the surface of the AlGaN barrier layer is responsible for improved device characteristics.     

Demonstration of Soliton Solutions of DNLS Equation by Liouville Theorem

In the inverse scattering transform (IST), the reflectionless Jost solutions are combined by their analytic properties in the complex spectrum parameter plane, and then can be shown to satisfy the two Lax equations indeed by Liouville theorem. So the corresponding soliton solutions certainly satisfy the nonlinear equation by compatibility condition. Especially the multi-soliton solutions of DNLS equation can be demonstrated in this way. PACS Numbers: 05.45.Yv, 02.30.-f, 11.10.Ef     

分光光度法研究钴(Ⅱ)-槲皮素配合物

利用分光光度法研究了槲皮素与Co（Ⅱ）形成配合物的最佳反应条件,测定了其配比和条件稳定常数。结果表明,在pH 4.7 HAc-NH₄Ac缓冲溶液中.槲皮素与Co（Ⅱ）配位,该配合物在584nm处有最大吸收。Co²⁺的浓度在2.0×10^-5—1.1×10^-4mol/L之间与吸光度呈线性关系。采用等摩尔连续变化法测得槲皮素-Co（Ⅱ）配合物的配位比为2:1,计算得到该配合物的条件稳定常数为2.7×10⁷L²·mol^-2。     

氦原子1s2p态的有限元近似能量

用有限元方法近似计算了1s2p态氦原子单态和三重态的能量,所得结果的相对误差:三重态为10^-6,单态为10^-4.这一结果比Schertzer^[1]对基态氦原子的相应结果稍好.有限元法导致的大型广义矩阵特征值问题,对于基态是对称的,而对于1s2p态是非对称的,给求解带来了难度.由波函数的图形说明,在有界区域上求Schrödinger方程的近似解是合理的.     

COMPLETENESS OF THE JOST SOLUTIONS IN THE CASE OF THE NLS+ EQUATION WITH NONVANISHING BOUNDARY CONDITION

In the case of the NLS⁺ equation with nonvanishing boundary condition, a complete set of the Jost solutions is chosen, and its completeness is shown by means of the Marchenko inverse scattering equation.     

钆钴非晶合金薄膜的电子衍射研究

用电子衍射方法研究了一些非晶钆钴合金磁性薄膜的结构,用Lorentz电子显微技术观察了其相应的磁结构。在所有薄膜的电子衍射图上均可清楚地看见七个弥散衍射环,其中两个最小的环分布在s<0.6?^-1(s=2sinθ/λ)的范围内。在不同的薄膜中观察到磁泡或平面畴结构。本文就这种由两种原子半径相差较大的元素,如稀土和过渡元素构成的非晶合金,讨论了如何只根据s<0.6?^-1范围内的衍射强度峰形,直接、定性地了解稀土与稀土原子、稀土与过渡族原子以及过渡族与过渡族原子之间最近邻配位数相对大小的问题。也讨论了钆钴薄膜相分离对磁各向异性的影响。 关键词：     

Optoelectronic properties of SnO_2 thin films sprayed at different deposition times

This article presents the elaboration of tin oxide(SnO_2) thin films on glass substrates by using a home-made spray pyrolysis system. Effects of film thickness on the structural, optical, and electrical film properties are investigated. The films are characterized by several techniques such as x-ray diffraction(XRD), atomic force microscopy(AFM), ultravioletvisible(UV–Vis) transmission, and four-probe point measurements, and the results suggest that the prepared films are uniform and well adherent to the substrates. X-ray diffraction(XRD) patterns show that SnO_2 film is of polycrystal with cassiterite tetragonal crystal structure and a preferential orientation along the(110) plane. The calculated grain sizes are in a range from 32.93 nm to 56.88 nm. Optical transmittance spectra of the films show that their high transparency average transmittances are greater than 65% in the visible region. The optical gaps of SnO_2 thin films are found to be in a range of 3.64 e V–3.94 e V. Figures of merit for SnO_2 thin films reveal that their maximum value is about 1.15 × 10-4-1?atλ = 550 nm. Moreover, the measured electrical resistivity at room temperature is on the order of 10-2?·cm.     

散弹噪声极限稳定度优于1×10-13τ-1/2的铷频标物理系统

近年来,铷原子频标研究取得长足进展,频率稳定度达到10^-13τ^-1/2量级.为进一步改善铷频标稳定度性能,本文设计了一种高信噪比物理系统.物理系统中的腔泡组件采用微波场磁力线与量子化轴方向高度平行的开槽管式微波腔,滤光泡和吸收泡独立控温.抽运光源采用了光学滤光和同位素滤光双重滤光方案.本文实测了背景光电流I₀和鉴频斜率K_d,结果分别为95 μA和7.7 nA/Hz,在此基础上计算物理系统的散弹噪声极限稳定度为7.5×10^-14τ^-1/2.研究结果表明,只要锁频环路的电子学噪声得到有效控制,铷频标的频率稳定度突破1×10^-13τ^-1/2,进入10^-14τ^-1/2量级是完全可能的.     

Theoretical and experimental investigations on the process ofhigh-pressure discharge development

The voltage breakdown behavior of a plane-parallel gap of 0.48-mm length filled with helium was examined at atmospheric pressure with admixtures of dry air at relative pressures of 0, 10^-4, 3×10^-4, and 10^-3. The initial stages of the breakdown were investigated by means of a quantitative model consisting of the electron, ion, and excited-particle conservation equations and the Poisson equation. The system of equations was solved for an applied voltage of 180 V, at one single partial pressure of the impurities. Two numerical routines were used for the solution: a commercial IMSL subroutine TWODEPEP, and a newly developed method of solution in several fractional steps. The results were compared and found to be in reasonable agreement although the new method indicated a somewhat slower rate of rise, particularly concerning electron density. The new method permits extension of the calculation up to electron densities equal to almost two orders of magnitude above the earlier limit     

LiNbO3和LiTaO3晶体Er3+/Yb3+掺杂水热外延层室温吸收光谱分析

本文引入与浓度和厚度有关的k_NL待定参数, 在J-O理论基础上, 对Er³⁺/Yb³⁺掺杂的LiNbO₃和LiTaO₃单晶衬底上 的多晶水热外延样品进行了基于吸收光谱的拟合计算. LiNbO₃:Ω₂=2.34× 10^-20 cm², Ω₄=0.77× 10^-20 cm², Ω₆=0.31×10^-20 cm², k_NL=4.32× 10^-2 mol·m^-2. LiTaO₃:Ω₂=1.68×10^-20 cm², Ω₄=0.84×10^-20 cm², Ω₆=0.45×10^-20 cm², k_NL=9.17×10^-3 mol· m^-2. 该方法可尝试推广到粉体或胶体等难以直接获得浓度和厚度数据的体系. 经上转换发光测试及光谱参数计分析认为Er³⁺/Yb³⁺离子的掺杂浓度比为1:1的情况下, 样品呈现绿色上转换发光光谱; 可尝试以降低基质声子能量的方法提高⁴I_13/2能级 对²H_11/2和⁴S_3/2能级的量子剪裁效率.     

Negative thermal expansion and photoluminescence in solid solution(HfSc)_(0.83)W_(2.25)P_(0.83)O_(12-δ)

A solid solution of(HfSc)_(0.83)W_(2.25)P_(0.83)O_(12-δ)is synthesized by the high-temperature, solid-state reaction and fastquenching method. It is shown that it possesses an orthorhombic structure with space group Pmmm(47) and exhibits negative thermal expansion(NTE) property with low anisotropy in thermal expansion. The coefficients of thermal expansion(CTEs) for a, b, and c axes are-1.41 × 10~(-6) K~(-1),-2.23 × 10~(-6) K-1, and-1.87 × 10~(-6) K-1, respectively. This gives rise to volume and linear CTEs of-3.10 × 10-6 K-1 and-1.03 × 10-6 K-1, respectively. Besides, it exhibits also intense photoluminescence from 360 nm to about 600 nm. The mechanism of NTE and the correlation of the PL with axial thermal expansion property are discussed.     

N-fold Darboux Transformation for Integrable Couplings of AKNS Equations

For the integrable couplings of Ablowitz-Kaup-Newell-Segur(ICAKNS) equations, N-fold Darboux transformation(DT) TN, which is a 4 × 4 matrix, is constructed in this paper. Each element of this matrix is expressed by a ratio of the(4N + 1)-order determinant and 4N-order determinant of eigenfunctions. By making use of these formulae,the determinant expressions of N-transformed new solutions p~([N ]), q~([N ]), r~([N ])and s~([N ])are generated by this N-fold DT.Furthermore, when the reduced conditions q =-p*and s =-r*are chosen, we obtain determinant representations of N-fold DT and N-transformed solutions for the integrable couplings of nonlinear Schr?dinger(ICNLS) equations.Starting from the zero seed solutions, one-soliton solutions are explicitly given as an example.     

Top Quark Flavor Changing Decay t→ cH^0 in Little Higgs Model

We study theoretically the quantum effects of the littlest Higgs model （LH） mediated by flavor changing one-loop Feynman diagrams on the rare decay process t→ cH^0. The comparison of the decay width in the LH model with that in the standard model （SM） is made. We find that the decay branch ratio of t→ cH^0 in the LH model is at most of the order-10^-12, which is two order larger than in the SM. The numerical results show that the difference between the branch ratios in the LH model and the SM is generally sensitive to the LH model parameters, such as symmetry breaking scale f, Higgs boson mass mH0, and x=v＇4f/v^2 in our chosen parameter space, but relatively insensitive to the value choice of the cosine of the mixing angle c and the ratio λ1/λ2.     

Low specific contact resistivity to graphene achieved by AuGe/Ni/Au and annealing process

Low metal-graphene contact resistance is important in making high-performance graphene devices.In this work,we demonstrate a lower specific contact resistivity of Au_(0.88)Ge_(0.12)/Ni/Au-graphene contact compared with Ti/Au and Ti/Pt/Au contacts.The rapid thermal annealing process was optimized to improve AuGe/Ni/Au contact resistance.Results reveal that both pre- and post-annealing processes are effective for reducing the contact resistance.The specific contact resistivity decreases from 2.5 × 10~(-4) to 7.8 × 10~(-5) Ω·cm~2 by pre-annealing at 300 ℃ for one hour,and continues to decrease to9.5 × 10~(-7) H·cm~2 after post-annealing at 490 ℃ for 60 seconds.These approaches provide reliable means of lowering contact resistance.     

锐钛矿金红石的高温原位X射线衍射研究

对TiO₂粉末进行了空气和真空条件下从室温到1200℃的加热原位X射线衍射实验, 得到了空气和真空条件下微米级锐钛矿颗粒转变为金红石的起始温度分别为850℃ 和855℃; 分别修正了空气条件下锐钛矿在(27–850℃)范围和金红石在(900–1200℃) 范围内的晶胞参数和真空条件下锐钛矿在(27–850℃)范围和金红石在(950–1200℃) 范围的晶胞参数, 从而得到了晶胞参数随温度变化的关系, 得到了锐钛矿和金红石在空气中和真空中的热膨胀系数, 并总结了热膨胀系数随温度变化的规律. 室温下锐钛矿在空气条件下的热膨胀系数为 α_a=4.55063×10^-6/℃, α_c=7.7543×10^-6/℃, β=16.85836×10^-6/℃; 真空下为 α_a=4.69429×10^-6/℃, α_c=9.02850×10^-6/℃, β=18.69688×10^-6/℃. 室温下, 金红石在空气条件下的热膨胀系数为 α_a=6.81243×10^-6/℃, α_c=8.71644×10^-6/℃, β=22.22178×10^-6/℃; 真空条件下为 α_a=6.05834×10^-6/℃, α_c= 8.39280×10^-6/℃, β=20.52362×10^-6/℃. 关键词： 2')" href="#">TiO₂ 原位X射线衍射 相转变 热膨胀     

Quasi Three-Body Decay of D Meson

The aim of this work is to provide a phenomenological analysis of the contribution of D~0 meson to K*(892)~0π~+π~-(K*(892)~0-→π~+K~-), K~-π~+ω(ω-→π~+π~-π~0) and K~-π~+?(?(1020)-→ K~+K~-) quasi-three-body decays. The analysis of mentioned multi-body decays is such as to factorize into the three-body decay and several channels observed. Hadronic three-body decays receive both resonant and non-resonant contribution. Based on the factorization method, there are tree and emission annihilation diagrams for these decay modes. In the case of D~0 to vector pseudoscalar states appeared in factored terms, the matrix elements of the vector and axial vector currents between the D~0 and PV mesons can be computed by using D~(*+)pole. Considering the non-resonant and resonant amplitude in our computation,the theoretical values of the branching ratio are(9.78 ± 0.46) × 10~(-3),(2.74 ± 0.17) × 10~(-2), and(3.53 ± 0.23) × 10~(-5), while the experimental results of them are(9.9 ±2.3) × 10~(-3),(2.7 ± 0.5) × 10~(-2), and(4 ± 1.7) × 10~(-5) respectively. Comparing computational analysis values with experimental values show that our results are in approximately agreement with them.     

PHOTO-ACOUSTIC MEASUREMENTS OF WATER VAPOR ABSORPTION COEFFICIENT IN UV SPECTRAL REGION

Data on the absorption coefficient of H₂O in binary mixture with N₂ in UV region of spectra are presented. With the use of the high sensitivity photoacoustic spectrometer, the following values of the absorption coefficient were found: 2.3×10^-9cm^-1·Pa^-1(λ=255 nm), 0.9×10^-9 cm^-1·Pa^-1(λ=271 nm), and 1.6×10^-9cm^-1 ·Pa^-1(λ=289 nm).     

Cabibbo-Suppressed Non-leptonic Decays of ∧c and Final State Interaction

With the diquark structure of ∧c, we investigate the branching ratio of ∧c→nπ^ and pπ^0. The results show that without considering the finM state interaction (FSI), the branching ratio of ∧c→pπ^0 is only of order 10^-6 whereas this ratio could reach 10^-4 and is at the same order as ∧c→nπ^ if taking into account the FSI effects. Concrete values depend on phenomenologicM parameters adopted in the calculations. These branching ratios can be measured in the experiments to come.