Ru原子高Rydberg态研究

本文描述用激光共振激发-场电离实验方法测定Ru原子的4d⁷(⁴F)ns(n=28—45)和4d⁷(⁴F)nd(n=26—48)系列Rydberg能级,并应用非线性拟合得到了Ru原子的第一电离阈值。采用相对论性自洽场方法对所得能级以及相应的量子亏损作了计算,理论与实验结果符合得很好。此外还将本文所得的第一电离阈值与已有数据作了比较。 关键词：     

氦原子低激发态的精细结构

利用变分法得到的氦原子低激发态1s2p能级的波函数，在考虑在氦原子自旋轨道相互作用的情况下，计算出1s2p能级的精细结构，与实验值比较，较为接近。     

Na原子d电子系列Rydberg态的精细结构计算

计算了Ｎa原子d电子系列Ｒｙｄｂｅｒｇ态的精细结构,获得与实验值相一致的结果。精细结构倒置的原因主要是介电子和原子实的交换作用,并发现原子实玫极化作用与有较大的贡献。计算过程中,在准相对论的框架下,用自旋极化模型,考虑了原子实与价电子的相互作用,采用自洽场方法,计算了原子实和价电子物径向波函数以及能量。原子;实采用自相互作用修正的Ｘα（ＳＩＣ－Ｘα）方法,价电子波函数考虑到了价电子的自旋－轨道耦合作     

氦原子自旋-其它轨道相互作用精细结构参数的理论计算

以多电子原子精细结构哈密顿的球张量形式和氦原子非相对论性能级结构理论为基础,借助不可约张量理论,建立了计算氦原子自旋-其它轨道相互作用精细结构参数的一种解析理论形式.完成了所有的角向积分和自旋求和计算,自旋-其它轨道相互作用精细结构参数最终用若干个径向积分来表示.以氦原子(1s2p)3P态为例,借用类氢形式的径向函数对这些径向积分进行了近似计算.计算结果表明:在氦原子的精细结构中,自旋-其它轨道相互作用与纯自旋-轨道相互作用的作用效果相反;在总自旋-轨道相互作用精细结构参数中,自旋-其它轨道相互作用起决定性作用,它决定着精细结构分裂的顺序.     

超冷nS Rydberg原子的态转移

本文从实验上研究了超冷nS Rydberg原子在外电场脉冲作用下的态转移现象. 采用双光子激发超冷基态原子制备超冷Rydberg原子, 通过脉冲场电离法探测超冷Rydberg原子的离子信号, 实验研究了由外加脉冲电场产生的nS能级和多重态的避免交叉, 获得了在外电场脉冲作用下nS态原子的态转移现象, 实验与理论计算的结果相一致. 关键词： Rydberg原子 态转移 能级避免交叉     

铕原子Rydberg态的场电离研究

利用三步激光共振激发结合场电离探测技术,系统地研究了铕原子归属于第一电离限4f76s 9S4的4f76snp Rydberg态的场电离过程,得到了铕原子4f76snp Rydberg 态的场电离光谱图。在光激发之后施加脉宽为0.2μs的脉冲电场,连续扫描电压得到场电离过程图。从4f76snp Rydberg态的场电离过程图谱中,可以精确地获得态的场电离阈,观察电场逐步从0到3 kV变化时原子的演化过程。特别是,受黑体辐射的影响,一些结构出现在了场电离光谱图上。     

Ru原子Rydberg态的能级结构

本文描述用激光共振激发-场电离方法测量Ru原子的4d⁷(⁴F)ns系列和4d⁷(⁴F)nd系列Rydberg态的能级结构,对可能的多重态的相对谱线强度进行了计算。理论计算与实验结果符合得很好,由此可以确定出观测到的各谱线的光谱项。 关键词：     

Sm原子奇宇称Rydberg态光谱

结合共振激发和场电离探测技术,通过总角动量量子数0→1→0→1的激发路径,研究了第一电离阈附近的Sm原子奇宇称Rydberg态4f⁶6snp(J=1)。首先,在45 200～45 500 cm^-1能量范围内共发现了94个奇宇称Rydberg能级。其次,通过对有效量子数和Rydberg能级结构特点的分析,将其中68个能级归属为3个束缚Rydberg系列,另外26个能级也给出了能级位置。然后,利用Rydberg-Ritz公式,对3个Rydberg系列分别进行了拟合,获得了Sm原子的电离阈为(45 519.61±0.79) cm^-1。最后,采用6种偏振组合激发,由偏振选择定则,进一步验证了这些奇宇称Rydberg态总角动量量子数为1。这些结果首次证实了场电离探测技术对Sm原子高激发Rydberg态的适用性,并且通过对奇宇称Rydberg系列拟合得到的Sm原子电离阈与文献中通过偶宇称Rydberg系列获得的值(45 519.64±1.39) cm^-1基本一致。     

利用自电离探测技术研究Sm原子Rydberg态光谱

采用孤立实激发与自电离探测技术相结合的方法对Sm原子偶宇称高激发态进行了系统研究.按照不同的自电离通道将所测数据进行了分类和比较,并进行了详细讨论.不仅报道了许多收敛于不同电离限的Rydberg态的能级位置和跃迁的相对强度等信息,而且还把处于同一能域内的Rydberg态和价态进行了辨识.另外,不但提供了一种有效识别不同类型的高激发态的鉴别技术,而且还对处于41800 cm^-1到43800 cm^-1能域内的Rydberg态和价态的光谱特性进行了详细分析和讨论. 关键词： 自电离探测 Rydberg态 Sm原子     

铯原子里德伯态精细结构测量

里德伯态光谱是测量里德伯态能级结构和中性原子间相互作用的常用技术手段,特别是高精度的里德伯光谱,可以测量室温原子气室中由偶极相互作用等导致的原子能级频移.在实验中利用反向的852 nm激光和509 nm激光实现了室温原子气室中铯原子6S_(1/2)—6P_(3/2)—57S(D)跃迁的级联双光子激发,实现了里德伯态原子的制备.基于阶梯型电磁诱导透明获得了铯原子里德伯态的高分辨光谱.实验中,基于速度选择的射频边带调制技术,对光谱信号进行了频率标定,测量了铯原子里德伯态57D_(3/2)和57D_(5/2)的精细分裂,分裂间隔为(354.7±2.5)MHz,与理论计算结果基本一致.速度选择的射频调制光谱可以实现里德伯态原子的能级分裂测量,其测量精度对于单光子跃迁的绝对激光频率不敏感;实验中影响57D_(3/2)和57D_(5/2)精细分裂间隔测量精度的主要因素是功率加宽导致的电磁感应透明信号的展宽和509 nm激光频率扫描的非线性.     

Velocity-selective spectroscopy measurements of Rydberg fine structure states in a hot vapor cell

A velocity-selective spectroscopy technique for studying the spectra of Rydberg gases is presented. This method provides high-resolution spectrum measurements. We present experimental results for a ladder system 6S_(1/2)→ 6P_(3/2)→ nS(D)electromagnetically-induced transparency involving highly-excited Rydberg states. Based on a radio-frequency modulation technique, we measure the hyperfine structure splitting of intermediate states and the fine structure splitting of Rydberg states in a room temperature ~(133)Cs vapor cell. The experimental data and theoretical predictions show excellent agreement.     

Fractal dynamics in the ionization of helium Rydberg atoms

We study the ionization of helium Rydberg atoms in an electric field above the classical ionization threshold within the semiclassical theory.By introducing a fractal approach to describe the chaotic dynamical behavior of the ionization,we identify the fractal self-similarity structure of the escape time versus the distribution of the initial launch angles of electrons,and find that the self-similarity region shifts toward larger initial launch angles with a decrease in the scaled energy.We connect the fractal structure of the escape time plot to the escape dynamics of ionized electrons.Of particular note is that the fractal dimensions are sensitively controlled by the scaled energy and magnetic field,and exhibit excellent agreement with the chaotic extent of the ionization systems for both helium and hydrogen Rydberg atoms.It is shown that,besides the electric and magnetic fields,core scattering is a primary factor in the fractal dynamics.     

The fine structure splitting of the level of lithium in Rydberg states

The Hamiltonian of the four-body problem for a lithium atom is expanded in series. The level shift and level formula of a lithium atom in Rydberg states are achieved by means of the calculation of polarization of the atomic core (including the contribution of dipole, quadrupole and octupole components). We also consider the effect of relativity theory, the orbital angular momentum L and the spin angular momentum S coupling scheme (LS coupling) and high-order correction of the effective potential to the level shift. The fine structure splitting (N=5-12, L=4-9, J=L±1/2) and level intervals in Rydberg states have been calculated by the above-mentioned formula and compared with recent experimental data.     

Lifetimes of Rydberg states of Eu atoms

The radiative lifetimes of the Eu 4f76snp(8PJ or10PJ)Rydberg states with J=5/2 and 11/2 are investigated with a combination of multi-step laser excitation and pulsed electric field ionization,from which their dependence on the effective principal quantum number is observed.The lifetimes of 21 states are reported along with an evaluation of their experimental uncertainty.The influence of blackbody radiation,due to the oven temperature,on the lifetime of the higher-n states is detected.The non-hydrogen behavior of the investigated states is also observed.     

改进的Numerov格式用于Rydberg原子结构的计算

为解决原子Rydberg态的数值计算问题,提出一种改进的Numerov算法.利用此算法计算了H原子n=10,20,……90,100各Rydberg态的能级值和平均半径,并与严格理论值进行了比较.研究结果表明,通过选择适当的Numerov格式,可得到所要求精度的能级和波函数.这为Rydberg原子的进一步研究提供了有效的计算方法.     

Precision spectroscopy of the helium atom

Persistent efforts in both theory and experiment have yielded increasingly precise understanding of the helium atom. Because of its simplicity, the helium atom has long been a testing ground for relativistic and quantum electrodynamic effects in few-body atomic systems theoretically and experimentally. Comparison between theory and experiment of the helium spectroscopy in 1s2p³P _J can potentially extract a very precise value of the fine structure constant á. The helium atom can also be used to explore exotic nuclear structures. In this paper, we provide a brief review of the recent advances in precision calculations and measurements of the helium atom.      

Investigation of odd-parity Rydberg states of Eu I with autoionization detection

Isolated-core-excitation (ICE) scheme and autoionization detection are employed to study the bound Rydberg states of europium atom. The high-lying states with odd parity have been measured using the autoionization detection method with three different excitation paths via 4f⁷6s6p[ ⁸P_5/2], 4f⁷6s6p[ ⁸P_7/2] and 4f⁷6s6p[ ⁸P_9/2] intermediate states, respectively. In this paper the spectra of bound Rydberg states of Eu atom are reported, which cover the energy regions from 36000~cm^-1 to 38250~cm^-1 and from 38900~cm^-1 to 39500 cm^-1. The study provides the information about level energy, the possible J values and relative line intensity as well as the effective principal quantum number n^* for these states. This work not only confirms the previous results of many states, but also discovers 11 new Rydberg states of Eu atom.     

Calculation of the fine structure of the level in Rydberg state of lithium

The level shift and level formula of lithium atom in Rydberg states are achieved by means of the calculation of polarization of the atomic core (including the contribution of dipole moment, quadrupole moment and octupole moment);meanwhile, the effect of relativity theory, the orbital angular momentum L and the spin angular momentum S coupling (LS coupling), and high order correction of the effective potential are considered. The some fine structures (N=5～12,L=4～9,J=L±1/2) and the corresponding level intervals in Rydberg states can be calculated by the above-mentioned level formula and compared with correlated experimental data.     

The theoretical and experimental investigations of Stark structure in sodium Rydberg states atoms

The experimental results of the Stark structure of Na in the vicinity of n~*=21-23 with the external electric field from 0 to 380V/cm are reported. The theoretical calculation of the stark levels of Na based on the atomic potential model are in good agreement with experiment. The limiting error between the theory and experiment turns out to be due to experimental uncertainty.