基于多体经典轨迹蒙特卡罗方法的H+,Li3+,Be4+,O7+与He原子电荷交换过程

经典轨迹蒙特卡罗(CTMC)方法是研究离子-原子碰撞系统电荷交换过程的常用方法,广泛应用于天体物理以及实验室等离子体环境下重粒子碰撞过程的研究.本文利用四体碰撞模型(4-CTMC)研究了包括两个束缚电子的四体碰撞过程,通过数值求解四体碰撞系统的哈密顿运动方程,计算了高电荷态入射离子(Li³⁺,Be⁴⁺和O⁷⁺)同氦原子在大能量范围的单、双电子电离和俘获截面.H⁺+He碰撞截面的计算中,在50—200 keV/amu的入射能区,4-CTMC的结果几乎重复了实验结果.在高电荷态入射情形下,4-CTMC计算的单电子电离和俘获截面值相较于三体碰撞模型(3-CTMC)在100—500 keV/amu的入射能区内与实验符合更好.尽管4-CTMC和3-CTMC忽略了电子关联,均高估了双电子电离和俘获截面(与实验值相比),但4-CTMC的结果更接近实验.     

3He(4He)与H2分子碰撞的同位素效应研究

用公认精确度较高的密耦近似方法计算了入射能量E=05eV时惰性气体原子³He(⁴He)与H₂分子替代碰撞体系的转动激发碰撞截面.通过分析³He(⁴He)-H₂碰撞体系分波截面和微分截面的差异,总结出在氦原子的同位素替代情形下³He(⁴He)-H₂碰撞体系分波截面和微分截面随分波数增加和同位素原子质量改变的变化规律. 关键词： 散射截面 密耦方法 同位素替代 散射角     

不同能量的氦原子与同位素分子H2(D2，T2)碰撞分波截面的理论计算

用Tang-Toennies势模型和密耦近似方法计算了不同能量下惰性气体原子He与H₂及其同位素D₂,T₂替代碰撞体系的振转激发碰撞截面. 通过分析He-H₂(D₂,T₂)各碰撞体系分波截面的差异,总结出在H₂分子的对称同位素替代情形下He-H₂(D₂,T₂)碰撞体系分波截面随量子数和体系 关键词： 散射截面 密耦方法 同位素     

质子与He+,Li++高能碰撞过程中电子俘获截面的理论计算

用OBK近似和CDW近似计算了H⁺+He⁺和H⁺+Li⁺⁺碰撞过程中电子俘获到激发态的分截面与俘获到基态分截面的比值，结果发现用OBK近似给出的比值和用CDW方法所给出的相应比值在高能区符合得很好．由此提出了一种用于计算高能H⁺与任一类氢离子碰撞的电子俘获总截面及任一激发态分截面的方法 关键词：     

电荷剥离截面的计算

采用二体碰撞近似(BEA)和托马斯费密近似(TFA),计算了多电荷离子(3Li2+,6C5+,10Ne+,18Ar+,36Kr+,54Xe+)的势函数分布和电子动量分布,以及它与中性原子H和He碰撞的电荷剥离截面. 关键词：     

H+和Ar11+激发Si的K壳层X射线发射研究

测量了50–250 keV H⁺和1.0–3.0 MeV Ar¹¹⁺ 轰击Si表面过程中辐射的X射线. 结果表明, 在Ar¹¹⁺入射的情况下, 引起了Si的L壳层上3, 4个电子的多电离.计算了Si的K壳层X射线产生截面, 并将两体碰撞近似(BEA), 平面波恩近似, ECPSSR理论计算与实验值进行了对比. ECPSSR理论与质子产生的截面数据能够很好地符合; 而考虑多电离后, BEA理论与Ar¹¹⁺的实验结果符合较好. 关键词： X射线 高电荷态重离子 多电离     

H+,He2+与Li原子碰撞中电子俘获总截面的程函近似计算

采用Li原子价电子的有效势对前置形式程函近似振幅公式进行了修正,提出有效势修正程函近似方法,并对H^＋和He²⁺与Li原子碰撞中的电子俘获总截面进行了计算,取得了与实验比较吻合的结果. 关键词：     

高电荷态离子N6+与He原子碰撞激发过程的实验研究

利用电子迴旋共振(ECR)多电荷离子源产生的高电荷态离子束和LHT-30VUV真空紫外单色仪,对N⁶⁺与He碰撞激发过程进行研究,观察到三种碰撞激发过程:(1)单电子俘获;(2)双电子俘获;(3)入射离子直接激发过程。 关键词：     

高电荷态Krq+与Al表面碰撞发射可见光的研究

利用低速(V≈0.01 V_Bohr)高电荷态Kr^q+ (q=8, 10, 13, 15, 17)离子轰击金属Al表面, 获得了碰撞过程产生的300–600 nm的光谱. 实验结果表明: 低能大流强(μA/cm²量级)离子束入射金属表面, 可产生溅射原子、离子和入射离子中性化后发射的可见光. 随着入射离子势能(电荷态)增加, 碰撞过程中发射谱线的强度增强. 与激发态3d能级相比, 较高的势能可以有效地激发Al原子的电子到较高4s能级. 关键词： 高电荷态离子 可见光发射 离子与表面作用     

Bi0.5Ca0.5Mn1-xCoxO3体系中的电荷有序和相分离

利用固相反应法制备了Bi_0.5Ca_0.5Mn_1-xCo_xO₃(0≤x≤0.12)系列多晶样品.研究了Co掺杂对Bi_0.5Ca_0.5MnO₃电荷有序的影响.结果表明,Co掺杂导致电荷有序相逐渐融化、铁磁相互作用的增强;当x≥0.08时,电荷有序转变峰完全消失,但残留的反铁磁电荷有 关键词： 钙钛矿锰氧化物 电荷有序 团簇玻璃 相分离     

Properties of the adiabatic energy curves for the ground states of H2+, HD+, and D2+

Equilibrium internuclear distances, energies, and force constants are reported for the diatomic molecules H₂⁺, HD⁺, and D₂⁺ at the adiabatic level of approximation. The differences between these values and those calculated previously at the Born-Oppenheimer level of approximation are analyzed.     

钪原子的自电离里德伯能级3d4s(1D2)nf2 D3/2,3d4s(1D2)nf2 F5/2和3d4s(1D2)np2 D3/2<

在多通道量子亏损理论框架下,利用相对论多通道理论,分别在冻结实近似和考虑偶极极化下计算钪原子的J^π=(3/2)^-,(5/2)^-的三个收敛于 3d4s(¹D₂)的自电离里德伯系列的能级.对3d4s(¹D₂)np²D_3/2和3d4s(^{1 关键词： 相对论多通道理论 多通道量子亏损理论 电子-电子关联 自电离里德伯系列}     

Energy dependence of the zero-range DWBA normalization of the 58Ni(3He, α) 58Ni reaction

Strong transitions in the ⁵⁸Ni(³He, α)⁵⁷Ni reaction were analyzed using both the zero-range and exact finite-range DWBA. Data considered covered a range of bombarding energies from 15 to 205 MeV. The zero-range DWBA described all data well when finite-range and non-locality corrections were included in the local energy approximation. Comparison of zero-range and exact finite-range calculations showed the local energy approximation correction to be very accurate over the entire energy region. Empirically determined D₀ values showed no energy dependence. A theoretical D₀ value calculated using an α wave function which reproduced the measured α rms charge radius and the elastic electron scattering form factor agreed well with the empirical values. Comparison was made between these values and D₀ values quoted previously in the literature.     

Corrections to the impulse approximation for π−d→nnγ

Corrections to the impulse approximation for π^?d→nnγ are calculated. The results substantiate the conclusions of McVoy and of Bander, that the energy dependence of the amplitude is determined precisely by the neutron-neutron ¹S₀ final state interaction. Corrections to the normalized spectrum are less than 2% up to nn energies greater than 1 MeV.     

Jet production in e+e− collisions to order α3 and α4 and including QCD corrections

Cross sections for e⁺e^?→jet₁ + jet₂ + X are calculated to order α³ and α⁴ in the electromagnetic coupling and to arbitrary order in α_s in the leading logarithm approximation of QCD. Physically the processes included are the emission of hard protons from the incident e^± followed by annihilation, photon-proton scattering and deep inelastic scattering on an electron. The experimental separation of the mechanisms on the basis of their different event structure is discussed.     

Photoionization of molecular oxygen in the X3Σg− and a1Δg states

Calculations are carried out, at similar levels of approximation, of the photoionization cross-sections for the ground X³Σ_g^? and metastable a¹Δ_g states of O₂ leading to the X²Π_g state of O₂⁺. Estimates, based upon measurements for the X³Σ_g^? state, are made of the photoionization cross-section of the a¹Δ_g state for transitions populating excited states of O₂⁺.     

R2Fe14B型永磁材料中第二磁晶各向异性常数对反磁化过程的影响

针对低温下各向同性Pr₂Fe₁₄B永磁材料的最小形核场问题，用数值 计算法和近似解 析解研究了第二磁晶各向异性常数K₂对最小形核场的影响.研究发现，尽管对于 Nd₂ Fe₁₄B永磁材料一级近似的解析解与数值计算结果很接近，但是对于低温下各向 同性P r₂Fe₁₄B永磁材料则至少要用二级近似下的解析解才能与数值计算 结果相接近.用有 关最小形核场的计算结果很好地解释了低温时各向同性Pr₂Fe₁₄B永 磁材料的矫顽力与最小形核场的关系. 关键词： 第二磁晶各向异性常数 形核场 矫顽力     

The AsO4−4 center in CsH2AsO4: A Halperin-Varma defect moving in a single well potential

The ESR of the AsO^4?₄ center in CsH₂AsO₄ is investigated from 4.2 K to 270K. The behavior of this paramagnetic center is essentially different from its behavior in the other members of the KDP family. Two properties of the center are remarkable: it seems to behave like a Halperin-Varma kind of defect and to move classically in a single-well potential which can be represented with very good approximation by a square well.     

The reactions 50,52Cr(d, 6Li) 46,48Ti at Ed = 651 MeV

The ^50,52Cr(d, ⁶Li) ^46,48Ti reactions have been studied at E_d = 65 MeV bombarding energy. Angular distributions of outgoing Li particles were measured for final states in ^46,48Ti nuclei from 15° to 50° (lab). These were compared with zero-range and finite-range DWBA calculations in an α-cluster pick-up approximation to obtain relative α-spectroscopic factors.     

近Bohr速度的152Eu20+入射Au表面产生的X射线谱

测量了动能为2.0–6.0 MeV的高电荷态离子¹⁵²Eu²⁰⁺ 入射Au表面产生的特征X射线谱, 结果表明, 相互作用不仅激发出了Au的 M_ζ, M_α和M_δ特征X射线, 还激发出了Eu的M_α X射线, 且X射线总产额随入射离子动能的增加而增加. 计算了Au的M壳层总的X射线产生截面, 并与理论模型的计算结果做了比较分析. 关键词： 高电荷态离子 X射线 产额 截面