激光拍频波加速器的参数选择

本文研究了激光拍频波加速器中的三波相互作用过程。结果表明:适当地选择参数σ=ω_p/(ω₁-ω₂)以及β=ω₂/ω₁(ω_p,ω₁,ω₂分别为等离子体频率及两束激光频率),即可用较弱的激光造成很强的拍频等离子体波,并使注入等离子体的电子获得显著的能量增益。 关键词：     

Tesla微混合器结构参数对混合强度的影响

针对Tesla微混合器混合原理,利用计算流体力学(CFD)模拟与分析软件对其进行了三维数值模拟.模型采用有限体积法离散、SIMPLEC算法进行层流计算.分析了结构参数的改变对该混合器混合效果的影响,并采用混合强度值作为衡量指标.分析结果显示,不同通道高宽比和分离通道入流角度等结构参数对该微混合器的混合效果有重要影响.模...     

声子之间的相互作用对量子线中磁极化子性质的影响

研究了量子线中弱耦合磁极化子的性质.采用线性组合算符和微扰法导出量子线中弱耦合磁极化子的基态能量.在计及电子在反冲效应中发射和吸收不同波矢的声子之间的相互作用时,讨论了量子线的受限强度、电子-LO声子耦合强度和声子之间相互作用对量子线中弱耦合磁极化子的基态能量的影响.数值计算结果表明:量子线中弱耦合磁极化子的基态能量随量子线的受限强度ω₀的增大而迅速增大.当受限强度ω₀取相同值时,电子-声子耦合强度α越大基态能量E₀越小,磁场的回旋频率ω_e越大基态能量E₀越大.在弱磁场情况下,当ω₀<0.5时,随着量子线的受限强度ω₀的减少p值迅速增大,即对于弱磁场声子之间相互作用的影响不能忽略.     

汞蒸汽中利用四波和频产生125nm附近可调谐真空紫外激光

以氩为匹配气体的汞蒸汽四波和频实验中,一束泵浦光(ω₁)与汞原子6¹S₀—7¹S₀严格双光子共振,当另一束泵浦光(ω₃)在汞原子7¹S₀—9¹P₁跃迁的蓝端调频时,产生可调谐的真空紫外(VUV)激光(ω₄=2ω₁+ω₃),其 关键词：     

非对称量子点中磁极化子性质的磁场和温度依赖性

采用Tokuda线性组合算符法和Lee-Low-Pines变换法,研究了温度和磁场对非对称抛物量子点中强耦合磁极化子性质的影响,简捷地得到了作为量子点的横向受限强度ω₁、纵向受限强度ω₂、电子-声子耦合强度α、外磁场的回旋频率ω_c和温度参数γ的函数的磁极化子的振动频率λ、基态能量E₀和有效质量m 关键词： 非对称量子点 强耦合磁极化子 磁场和温度依赖性     

NCO异构体结构与分析势能函数

在B3LYP/6-31+G（d）水平上,对NCO分子的各种可能结构进行几何优化,得到了NCO及其异构体分子CNO和CON基态结构都是C_∞v,电子态为X²Ⅱ,NCO分子的平衡核间距R_NC=0.1230 nm,R_CO=0.1186 nm,离解能D_e=13.40 eV,并计算出谐振频率ω₁=1293.44 cm^-1,ω₂（A′）=484.73 cm^-1,ω₂（A″）=559.72 cm^-1,ω₃=1988.41 cm^-1,Renner-Teller参数ε=-0.1429,计算值与实验值吻合较好.在此基础上,应用多体项展式理论,单体项中首次引入开关函数,三体项以NCO,CNO基态结构与性质为依据,拟合给出了NCO分子的基态分析势能函数,其等值势能图准确再现了NCO,CNO分子基态结构与特征,并与优化结果完全一致.     

吡啶非谐振耦合(费米共振)的二维相关拉曼光谱研究

费米共振(FR)是一种广泛存在于分子内和分子间的分子振动耦合和能量转移现象。研究了吡啶与乙醇混合溶液中的吡啶分子内费米共振效应(ν1～ν₁₂,ν₁+ν₆～ν₈),发现了吡啶乙醇存在分子间氢键(O—H…N),通过费米共振参数变化和二维相关拉曼光谱(2DCRS)揭示了吡啶乙醇溶液相互作用机理。ν₁～ν₁₂,ν₁+ν₆～ν₈通过非谐相互作用引起能量转移,从而导致费米共振参数的变化。2DCRS可以提供更多费米共振信息,阐明了费米双峰的相互作用机制。     

Hg蒸汽中通过双光子共振四波差频产生调谐真空紫外辐射

利用Hg原子6¹S₀—6¹D₂和6¹S₀—6³D₂双光子共振的四波差频(2ω₁—ω₃),获得了真空紫外相干辐射(ω₄)。当入射光之一(ω₃)波长调谐时,产生的真空紫外光也是调谐的,调谐范围为184.9-187.5nm.本文对非线性频率变换过程的机 关键词：     

激光平面靶3ω0/2谐波空间精细结构的时间和光谱特性

我们从实验上观察到3ω₀/2谐波沿90°辐射精细结构,并从运动细丝底部附近n_c/4处辐射3ω₀/2谐波来解释3ω₀/2谐波细丝结构的存在;从运动的细丝底部对TPD带来的Doppler修正解释3ω₀/2谐波的双峰结构以及红强蓝弱的特点,数量上对红移、蓝移的估算与实验大体相符。用宽带激光打靶,由于靶面照明均匀及宽频带作用,细丝不易形成,对抑制TPD产生的超热电子可能是有益的。 关键词：     

描述蠕变过程中内耗的四参量模型

实验表明:蠕变过程中的内耗兼有Maxwell二参量模型的性质和滞弹性三参量模型的性质。本文提出一个用以描述蠕变过程中内耗的四参量模型。由此模型推导出的内耗表达式为Q^-1=1/(ωτ₁)+△(ωτ₂)/(1+ω²τ₂²),式中ω为测量圆频率,τ₁和τ₂分别为粘弹性内耗和滞弹性内耗的弛豫时间,△为弛豫强度。这个内耗表达式可以满意地说明蠕 关键词：     

Effect of lateral structure parameters of SiGe HBTs on synthesized active inductors

The effect of lateral structure parameters of transistors including emitter width, emitter length, and emitter stripe number on the performance parameters of the active inductor(AI), such as the effective inductance Ls, quality factor Q,and self-resonant frequency ω_0 is analyzed based on 0.35-μm Si Ge Bi CMOS process. The simulation results show that for AI operated under fixed current density JC, the HBT lateral structure parameters have significant effect on Ls but little influence on Q and ω_0, and the larger Ls can be realized by the narrow, short emitter stripe and few emitter stripes of Si Ge HBTs. On the other hand, for AI with fixed HBT size, smaller JCis beneficial for AI to obtain larger Ls, but with a cost of smaller Q and ω_0. In addition, under the fixed collector current IC, the larger the size of HBT is, the larger Ls becomes, but the smaller Q and ω_0 become. The obtained results provide a reference for selecting geometry of transistors and operational condition in the design of active inductors.     

球形平均场加四极-四极和对力模型在单j壳内的量子相交叉行为(英文)

介绍了单j壳的球形平均场加几何四极-四极和标准对力模型的量子相交叉行为。在单j=15/2的壳内,计算了随模型控制参数变化的多个物理量如低激发能级、激发态间重叠积分、低激发态间的B（E2）比值和电四极矩比值。结果显示,在类转动到对激发相的演化中,多个物理量在交叉区存在非常明显的变化,如B（E2;4₁ → 2₁）/B（E2;2₁ → 0_g）,B（E2;4₂ → 2₁）/B（E2;2₁ → 0_g）等,并且这些变化在核子数达到半满壳时尤为显著。此外,尽管当j较小时,由几何四极-四极相互作用得到的低激发能级不满足转动谱规律,但当j值足够大时,这些低激发能级满足转动谱规律。The analysis of the quantum phase crossover behavior in the spherical shell model mean-field plus the geometric quadrupole-quadrupole (Q·Q) and standard pairing model within a single-j shell is reported. Several quantities, such as low-lying excitation energies, the overlaps of excited states, ratios of some B(E2) and electric quadrupole moments of some low-lying states as functions of the control parameter of the model in a j=15/2 shell are calculated. The results show that there are noticeable changes in the crossover region of the rotational-like to the pair-excitation phase transition, such as B(E2;4₁ → 2₁)/B(E2;2₁ → 0_g) and B(E2;4₂ → 2₁)/B(E2;2₁ → 0_g), especially in the half-filling case. Though the low-lying excitation energies generated from the geometric quadrupole-quadrupole interaction not satisfy the pattern of a rotational spectrum when j is small, these energies follow the pattern of a rotational spectrum when j is sufficiently large.     

金刚石晶格上的对角无序与非对角无序非晶量子点

报道金刚石晶格上对角无序与非对角无序非晶量子点的理论研究，用简单的紧束缚哈密顿量描述模型的电子结构，用ｒｅｃｕｒｓｉｏｎ方法求解哈密顿方程，用边界条件对本征值的影响判断局域化，研究发现，带边为扩展态时，带宽的变化趋势与晶态量子点类似；带边为局域态时，尺寸超过某一临界长度后，带宽不变，但带边态密度随尺寸增大而增大。还研究了非晶量子点的介电函数虚部ε₂（?ω）。与扩展态对应的ε₂（?ω），对尺寸变化较敏感。与局域态对应的ε₂（?ω），当尺寸大于 关键词：     

One- and Two-Mode Combination Squeezing Operator for Two Harmonic Oscillators with Coordinate-Momentum Coupling

By virtue of the technique of integration within an ordered product of operators, we derive the normal ordering expansion of a one- and two-mode combination squeezing operator for two harmonic oscillators with coordinate- momentum coupling. It turns out that this squeezing operator just diagonalizes the Hamiltonian H=p^21/2m1＋m1ω^21x^21/2＋p^222m2＋m2ω^22x^22/2-λx2p1 so its ground state is a one- and two-mode combination squeezed state. Quantum fluctuation in the ground state is calculated.     

二维各向异性谐振子的第三个独立守恒量及其对称性

二维各向异性谐振子和两分振子的能量是守恒的, 但三个守恒量中只有其中两个是独立的. 当频率比ω₁/ω₂ 为有理数时, 系统存在第三个独立的守恒量.本文用扩展Prelle-Singer 法得到五个典型谐振子的第三个独立守恒量, 并讨论了与守恒量相应的Noether对称性与Lie对称性.     

Tb-Zn一维配位聚合物的合成及发光性质

采用流变相反应法合成了具有良好发光性能和可溶性的一维链结构配位聚合物Tb(Fur)₃(H₂O)₂.DMF和Tb₂Zn(Fur)₈(H₂O)₂及四核异金属配位聚合物Tb₂Zn₂(tpca)₁₀(phen)₂,用单晶和粉末X射线衍射法表征了晶体结构。在这些配合物中Tb³⁺分别是8配位、9配位和7配位,金属离子之间都是通过羧酸根-CO₂^-基团成桥连结。研究了配合物的紫外-可见吸收光谱、荧光激发和发射光谱,讨论了配位结构对荧光光谱性质的影响。     

OH,OCl,HOCl(~1A′)的从头算与势能曲线

采用Gassian09程序包中的多种方法对OH,OCl,HOCl分子的基态结构进行优化计算,优选出QCISD/6-311G（2df）,B3P86/6-31 1+G（2df）方法分别对OH（X²∏）,OCl（X²∏）分子进行计算,得到平衡核间距R_OH=0.09696nm,R_OCl=0.1569 nm,谐振频率w（OH）=3745.37 cm^-1,e（OCl）=892.046 cm^-1,与实验结果非常符合.用Murrell-Sorbie势能函数对OH和OCl分子的扫描势能点进行拟合,其扫描点都与四参数Murrell-Sorbie函数拟合曲线符合得很好.优选出QCISD（T）/D95（df,pd）方法对HOCl分子进行计算,得到基态为X¹A’,键长R_OH=0.0966 nm,键角∠HOCl=102.3°,谐振频率w₁（a₁）=738.69 cm^-1,w₂（b2）=1260.25 cm^-1,离解能D_e=2.24 eV.通过比较发现这些结果与实验值符合得很好,并优于文献报道的结果.随后计算出了力常数,在此基础上,推导出HOCl分子的多体展式势能函数.报道了HOCl分子对称伸缩振动势能图中在H+OCl→HOCl反应通道上有一鞍点,H原子需要越过1.74 eV的能垒才能生成HOCl的稳定结构,在Cl+OH→HOCl通道上不存在明显势垒,容易形成稳定的HOCl分子.     

Electroreflectance of p-type GaAs

The electroreflectance spectra of p-type GaAs in photon energies from 1.3 to 3.5 eV have been investigated at temperatures from 300° down to 25°K. Measurements of electroreflectance have been performed by the method using the interface potential of GaAs-SnO₂ heterojunction. Both signals of an exciton and the fundamental edge have been separated in the low temperature spectra, and an additional structure which may be associated with a localized state has been also observed below the fundamental edge. The similar structures with weak intensity appear near the spin-orbit split off edge. The line shapes of electroreflectance spectra which are related to Λ₃−Λ₁ transition and its spin-orbit split off edges are explained by the mixed electro-optical spectra of M₁() and M₁() type critical points including the effect of thermal broadening. A method of estimating the thermal broadening factor from the temperature dependences of the electroreflectance spectra associated with Λ₃−Λ₁ transition edge is also presented.     

Effective AC and DC Responses of Nonlinear Composites at Higher Concentration

For higher concentration of inclusions, an effective medium approximation （EMA） method is used to investigate the bulk effective response of weakly nonlinear composites, which are subject to the constitutive relation of electric displacement and electric field, Dα = εαE ＋Xα｜E｜^2 E. As an example of three dimensions, under the external AC and DC electric fields Eapp = Eα（1 ＋ sinωt）, we have derived the general effective nonh＇near response of composites by the EMA method for higher concentration of spherical inclusions. Furthermore, the effective nonlinear responses at harmonics are predicted.