SrI 4dnp和4dnf奇宇称J=1系列自电离态光谱

用激光三步激发方法,以4d^{2 3}P₀价态为中间态,观察了Sr原子4dnp和4dnf奇宇称J=1系列自电离态光谱,在59570—60300cm^-1范围内,测定了60个自电离能级,其中大多数可归属于分别收敛于4d²D_3/2和4d²D_5/2电离限的6个自电离系列,讨论了光谱线的线型和组态相互作用。 关键词：     

Ba原子6pnd(J=1, 3)自电离光谱的实验研究

采用三台可调谐激光实施孤立实激发,分三步将处于基态的Ba原子激发到6p_1/2nd(J=1,3)和6p_3/2nd(J=1,3)自电离态上,获得了分别从6snd¹D₂(n=7—15)和6snd³D₂(n=7—12) 激发而得到的6p_1/2nd(J=1,3)和6p_3/2nd (J=1,3)自电离光谱,重点对主量子数n较低的自电离态进行了实验研究. 通过光谱的线形拟合得到了上述能级的位置和宽度等数据,进而获得了量子亏损和约化宽度等信息. 通过对不同系列的自电离光谱的分析和比较,详细讨论了这些自电离态的光谱特征及其复杂光谱结构的成因. 关键词： 孤立实激发 组态相互作用 自电离态     

Au原子高Rydberg态场致电离的实验研究

利用电热法将含金物质加热,产生Au原子束,再以两束UV脉冲激光垂直照射,将处于基态的Au原子共振激发至高Rydberg态。滞后于激光脉冲200ns的高压脉冲电场(6500V/cm)加到反应区,使处于Rydberg态的Au原子电离。激光波长在一定范围内扫描,共测出了Au原子的n²D_3/2(n=18—38)和n²S_1/2(n=21—34;36—38)两通道的38条能级的位置。用参数拟合得到²D_3/2和²S_1/2两系列的极限分别为:E_D=74409.8(3)cm^-1,E_S=74410.0(2)cm^-1,计算了每条能级的量子亏损。我们的实验还证明了场电离是一种十分有效的电离手段,比用通常的激光光电离效率要高得多。这在共振电离谱学(RIS)的研究中是一种很有效的方法。 关键词：     

中低能非全裸C离子与He原子的碰撞研究

采用反冲离子飞行时间-散射离子位置灵敏符合测量技术，测量了能量范围在0.7v₀—4.4v₀(v₀为玻尔速度)的碳离子C^q+(q=1—4)与He原子碰撞过程不同出射道靶原子的双电离与单电离截面比R，包括入射离子不损失电子(直接电离)的出射道(R_q,q),入射离子俘获一个电子的出射道(R_q,q-1)和入射离子损失一个电子的出射道(R_q,q+1)，并研究了R随入射C离子的能量及电荷态的变化关系.实验表明，对给定电荷态的入射离子，靶原子的双电离与单电离截面比R与出射道有很强的依赖关系，即R_q,q<R_q,q+1<R_q,q-1.直接电离出射道截面比R_q,q与入射离子电荷态几乎无关，而入射离子俘获一个电子的出射道和损失一个电子的出射道靶原子双电离与单电离截面比R_q,q-1和R_q,q+1却与入射离子电荷态有很强的关系.采用原子极化理论和电子屏蔽与反屏蔽作用对实验结果进行了解释. 关键词： 离子-原子碰撞 电离 截面比     

低电荷态离子原子碰撞过程中的转移电离机理的研究

介绍了使用位置灵敏技术和飞行时间方法研究中低能低电荷态离子-原子碰撞过程中转移电离与单电子俘获过程.对于确定的入射离子电荷态,通过理论分析及与实验数据对比给出了转移电离与单电子俘获截面比R_TS随着入射离子速度V_P的变化规律和转移电离过程中电离的电子主要来自靶原子的最外亚壳层. 关键词： 转移电离 逃离半径 电离半径 俘获半径     

铯47D精细能级超冷里德堡原子自由演化的动力学研究

用连续窄线宽激光器将超冷铯里德堡原子分别激发到47D_3/2, 47D_5/2精细态, 观察了处于里德堡精细态的铯原子向超冷铯等离子体自由演化的过程, 详细对比了不同精细态的铯里德堡原子预电离时间、电离速率以及等离子体的转化效率. 将里德堡原子快速转化为等离子体的过程解释为局域势阱内由预电离产生的电子与里德堡原子的快速碰撞导致的雪崩电离.     

水溶液中稀土离子与甘氨酸、丝氨酸、天冬氨酸作用的13C NMR研究

测定了酸性水溶液中甘氨酸、丝氨酸和天冬氨酸稀土络合物(Ln=La、Pr、Nd、Eu、Tb、Dy、Ho、Er、Tm和Yb)的¹³C诱导位移。对位移试剂的分析指出,三种氨基酸通过α-羧基以双齿形式配位于稀土,配位键长为0.23nm~0.25nm,天冬氨酸的γ-羧基也是配位基团。由本文与文献中已报道的各种氨基酸稀土络合物的¹³C诱导位移的系统分析表明,配体¹³C超精细偶合常数A值和结构因子G值有如下规律:(1)│A(C₀)│<│A(C_α)│;A(C₀)为正,A(C_α)为负;(2)│G(C₀)│>│G(C_α)│;配体碳核的G均为负值。     

主动型氢原子钟原子弛豫时间的测量和分析

氢原子钟的原子弛豫时间是原子系统经过选态去除基态超精细能级（F = 0,m_F = 0）态和（F = 1,m_F = −1）态原子后,部分氢原子从（F = 1,m_F = 0）态跃迁至（F = 0,m_F = 0）态直至原子系统达到平衡状态所需的时间,该参数反映了原子的寿命,并直接影响氢原子钟的稳定度指标.为了测量主动型氢原子钟的弛豫时间,进而评估其性能,通过Raspberry Pi（RPI）产生时序信号,控制数字衰减器和电离源供电电路的继电器,从而控制微波探测信号的开启和原子束流的通断,并与数据采集等电路组成了氢原子自由感应衰减测试系统.通过对采集的自由感应衰减信号建模拟合,测算了氢原子钟的弛豫时间.该方法对于评估和优化原子线宽,改进主动型氢原子钟稳定度指标具有重要的参考意义.     

Cs原子里德伯态Stark能级场电离阈值与｜ml｜关系的测定

报道Ｃｓ原子里德伯态Ｓｔａｒｋ能级场电离阈值与｜ｍ_l｜依赖关系的实验研究结果，从实验上同时测得Ｃｓ原子｜ｍ_l｜＝０，１，２三种态的电离阈值表达式。 关键词：     

氯化氢共振多光子电离光谱：F1Δ2态的光谱微扰分析

通过共振多光子电离-飞行时间法, 记录了氯化氢分子在84800-85700 cm^-1范围内, F¹Δ₂ (v’=1) 里德堡态以及V¹∑⁺ (v’=13, 14) 离子对态的电离产物H⁺, ³⁵Cl⁺, H³⁵Cl⁺ 及其同位素的光谱数据. 由于受离子对态V¹∑⁺ 的作用, F¹Δ₂ (v’=1)态呈现出明显的近共振相互作用特性. 为了分析F¹Δ₂与V¹∑⁺态之间存在的光谱微扰, 基于光解离电离通道的分析, 并针对F¹Δ₂ (v’=1)态离子信号比的变化, 将离子信号二能级作用模型优化到三能级的作用模型, 计算得到了微扰强度值为0.6 cm^-1, 预解离系数γ为0.025. 此外, 对于F¹Δ₂ (v’=1) 与V¹∑⁺ (v’=13, 14)态的三个振动能级的光谱峰位置, 采用光谱解微扰法拟合, 同样得到了类似的微扰强度和去微扰后的各光谱参数. 研究表明, 激发至F¹Δ₂ (v’=1)态得到的H⁺, Cl⁺ 离子主要是该态通过与离子对态耦合作用而产生, 而F¹Δ₂ (v’=1) 态光谱位置偏移不仅受离子对态而且还受其他里德堡态作用的影响. 同时, 非零γ 值证实了F¹Δ₂态预解离的存在. 关键词： 光解离电离 里德堡态 离子对态 光谱微扰     

| m | Partial wave treatment for two-dimensional Coulomb-scattering and Regge pole

The symmetry and |m| partial-wave analysis for two-dimensional (2D) Coulomb-scattering is investigated. As a function of energyE, the |m| partial-wave scattering amplitudef _|m|(θ) is analytically continuated to the, negativeE (complexk) plane, and it is found that the bound state energy eigenvalues (E<0) are just located at the poles off _|m|(θ) on the positive imaginaryk axis as is expected. In addition, as a function of |m|,f _|m|(θ) is analytically continuated to the complex |m| plane, the bound state energy eigenvalues are just located at the poles off _|m|(θ) on the positive real |m| axis.     

Na原子高里德堡态的辐射寿命

用可调谐激光两步激发Ｎａ原子高激发发里德堡态布居，在光激发后施加脉冲电场测量激发态的场电离阈，利用阈值电场和延迟场电离方法测定了ｎｓ（ｎ＝２０～２４）和ｎｄ（ｎ＝１９～２３）态的寿命值，并与计算值进行了比较，对影响寿命的因素作了讨论。     

Dependence of |V ub/Vcb| on Fermi momentump F in ACCMM model

The Gaussian width of Fermi momentum,p _F, is the most important parameter of the ACCMM model, and its value is essential in the determination of |V _ub/V_cb| because the experimental analysis is allowed only at the end-point region of inclusive semileptonicB-decay spectrum. We extract the value of |V _ub/V_cb| as a function ofp _F. We also calculate the parameterp _F in the relativistic quark model using the variational method, and obtainp _F=0.54 GeV which is much larger than the commonly used value, ∼0.3 GeV, in experimental analyses. When we usep _F=0.5 GeV instead of 0.3 GeV, the value of |V _ub/V_cb| from ACCMM model is increased by a factor 1.81, and can give a good agreement with Isgur et al. model.     

Regge cuts and large-|t| pp scattering

It is shown that recent measurements of the large-|t| pp elastic-scattering differential cross section at FNAL and CERN-ISR agree with earlier predictions based on the dominance of a pomeron pole(P) with αp(t) = 1.067 + 0.10 t, and a P ? P cut, out to the largest measured |t| values (12 GeV²). Some of the problems raised by this success are discussed.     

Study of deuterium and hydrogen distributions in Ta|CD<Subscript>2</Subscript>|Ta,Ta|Ta|CD<Subscript>2</Subscript>|Ta|Ta,and Nb|CD<Subscript>2</Subscript>|Nb assemblies after exposure to high-temperature argon plasma

Assemblies made of Ta|CD₂|Ta, Ta|Ta|CD₂|Ta|Ta and Nb|CD₂|Nb foils are irradiated with pulses of high-temperature argon plasma created by means of a “Plasma Focus” setup. The irradiated foil samples are investigated by recording the recoil nuclei of hydrogen and deuterium. It is found that hydrogen and deuterium are redistributed in foil stacks. The ultradeep penetration of light gas impurities (hydrogen and deuterium) can be explained by the influence of shock waves on the foils and accelerated diffusion under an external force.     

Channel-combination method for phase-based |B1+| mapping techniques

PurposeThe aim of this study was to propose a channel combination method for |B₁⁺| mapping methods using phase difference to reconstruct |B₁⁺| map.Theory and methodsPhase-based |B₁⁺| mapping methods commonly consider the phase difference of two scans to measure |B₁⁺|. Multiple receiver coils acquire a number of images and the phase difference at each channel is theoretically the same in the absence of noise. Affected by noise, phase difference is approximately governed by Gaussian distribution. Considering data from all channels as samples, estimation can be achieved by maximum likelihood method. With this method, all phase differences at each channel are combined into one. In this study, the proposed method is applied with Bloch-Siegert shift |B₁⁺| mapping method. Simulations are performed to illustrate the phase difference distribution and demonstrate the feasibility and facility of the proposed method. Phantom and vivo experiments are carried out at 1.5 T scanner equipped with 8-channel receiver coil. In all experiments, the proposed method is compared with weighted averaging (WA) method.ResultsSimulations revealed appropriateness of approximating the distribution of phase difference to Gaussian distribution. Compared with WA method, the proposed method reduces errors of |B₁⁺| calculation. Phantom and vivo experiments provide further validation.ConclusionConsidering phase noise distribution, the proposed method achieves channel combination by finding the estimation from data acquired by multiple receivers coil. The proposed method reduces |B₁⁺| reconstruction errors caused by noise.     

Collision of Rydberg atom A** with atom B in the ground electronic state. Optical potential

A method for calculating the complex optical potential of slowly colliding Rydberg atom A^** and neutral atom B in the ground electronic state is suggested. The method is based on the asymptotic approach and the theory of multichannel quantum defects, which uses the formalism of renormalized Lippmann-Schwinger equations. The potential is introduced as the 〈q|V _opt|q〉 matrix element of the optical interaction operator, for which the integral equation is derived, and is calculated in the basis set of free particle wave functions |q〉. Fairly simple equations for the shift and broadening of the ionic term are obtained, and the principal characteristics of these equations are analyzed. By way of illustration, the optical potential of the Na^**(nl)+B systems, where B is a rare gas atom, is calculated.     

Linewidths of HCl broadened by CO2 and N2 and CO broadened by CO2

High resolution measurement of the linewidths of HCl broadened by CO₂ and N₂ and CO broadened by CO₂ have been performed in both the 1-0 and 2-0 bands of HCl and the 2-0 band of CO. The data were analyzed by the direct and the peak absorption methods. Values of the linewidths obtained by the two methods are in good agreement. For |m| ≤ 3, for the case of HCl + CO₂, the agreement is good for the values obtained in both bands of HCl. However for |m| > 3, the HCl + CO₂ linewidths in the 1-0 band are smaller than the corresponding lines in the 2-0 band by as much as 11% for |m| = 9. Lines (|m| ≤ 3) of the 1-0 and 2-0 bands of HCl broadened by CO₂ were also analyzed in terms of the super-Lorentzian line profile proposed by Varanasi, S. K. Sarangi, and G. D. T. Tejwani (J. Quan. Spectr. Radiative Transfer12, 857 (1972)) and the Lorentzian profile. The results indicate that near the line center (within 3γ), the shape of HCl + CO₂ lines are Lorentzian.     

Anomalies in the microwave spectrum of SiH3CCH in the 3ν10 state

The microwave spectrum of silyl acetylene in the 3ν₁₀ state has been investigated from 9 to 117 GHz. After an assignment by graphical methods, the analysis has been carried out by a diagonalization of the energy matrix. Many anomalies appear in that spectrum; in particular, the |l| = 1 and |l| = 3 states cannot be fitted with a unique set of parameters.