Two-photon exchange corrections to the 2p(1/2)-2s transition energy in Li-like high- Z ions

A rigorous QED calculation of the two-photon exchange corrections to the 2p(1/2)- 2s transition energy in Li-like high- Z ions is presented. The contribution due to an exchange by more than two photons is evaluated within the Breit approximation. The resulting theoretical value of the 2p(1/2)- 2s transition energy in Li-like uranium is found to be 280.44(20) eV.     

Precision measurement of the 2p-1s transition wavelength in muonic 13C

With the bent-crystal spectrometer at the SIN muon channel we have measured the wavelength of the 2p-1s transition in muonic ¹³C with a precision of 13 ppm. The result for the $\text{2}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{-1}\text{S}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ transition is $\text{λ(2}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{-1}\text{s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{) = 16.46055 ± 0.00021}\text{pm}$; it is interpreted in terms of a short-range muon-nucleon interaction not included in standard QED calculations.     

Improved measurement of the 1s2s 1S0-1s2p 3P1 interval in heliumlike silicon

Using colinear fast-beam laser spectroscopy with copropagating and counter-propagating beams we have measured the 1s2s 1S0-1s2p 3P1 intercombination interval in 28Si12+ with the result 7230.585(6) cm{-1}. The experiment made use of a dual-wavelength, high-finesse, power build-up cavity excited by single-frequency lasers at 1319 and 1450 nm. The result will provide a precision test of ab initio relativistic many-body atomic theory at moderate Z.     

高剥离类钠离子3s2S—3d2电四极矩E2光谱跃迁的理论计算

 利用全相对论性多组态Dirac-Fock平均能级方法系统地计算了高剥离类钠离子3s²S—3d²D(Z=14～103）电四极矩E2光谱跃迁的能级间隔，跃迁几率和振子强度，计算中考虑了核的有限体积效应，Breit修正和QED修正，所得结果和最近的实验数据及理论计算值进行了比较，计算结果表明：高原子序数的高荷电离子的电四极矩E2光谱跃迁的跃迁几率和中性原子的电偶极E1的相当，在ICF和MCF高温高密度激光等离子体中，电四极矩E2光谱跃迁过程不容被忽视。     

Laser spectroscopy of the 1s22s2p 3P2-3P1 transition in beryllium-like argon using the Oxford EBIT

A study of the 1s²2s2p ³P₂-³P₁ fine-structure transition in beryllium-like argon is planned on the Oxford electron beam ion trap (EBIT), using laser-induced resonance. This transition wavelength was measured previously as 594.373(4) nm, which is accessible using a dye laser. The ions are produced and excited in the EBIT and are confined during laser irradiation using the magnetic trapping mode. The ³P₂ level population is depleted by the laser and by subsequently monitoring the emitted fluorescence a laser resonance signal can be obtained. This revised version was published online in July 2006 with corrections to the Cover Date.     

类镁离子3s21S0-3s3p1P1(Z=15～103)光谱跃迁的能级和跃迁几率的相对论多组态计算

利用全相对论性多组态Dirac-Fock平均能级(MCDF-AL)方法系统地计算 了高离化类镁离子3s21S0-3s3p1P1(Z=15～103)跃迁的能级间隔和 跃迁几率，计算中考虑了重要的核有限体积效应，Breit修正和QED修正，所得结果和最近的 实验数据及其它理论计算值进行了比较。     

弛豫与关联效应对NII离子2s22p3s3P1—2s22p21D2与2s22p3s1P1—2s22p23P0,1,2自旋禁戒跃迁概率的影响

用多组态Dirac-Fock方法，并系统考虑相对论效应、电子关联、弛豫效应等重要贡献，计算了NII离子2s22p3s 3P1—2s22p21D2和2s22p3s 1P1—2s22p23P0,1,2自旋禁戒跃迁概率和振子强度-通过比较计算证实：弛豫和关联效应对禁戒跃迁概率的影响非常大，考虑了这些效应后，计算结果有显著的改善-由跃迁概率和振子强度的计算值推断，2s22p3s 3P1—2s22p21D2的谱线强度应该比原有的理论预言值小- 关键词： 跃迁概率 多组态Dirac-Fock方法     

Precision microwave measurement of the 2 3P1-2 3P2 interval in atomic helium

The 2 3P1-to- 2 3P2 interval in atomic helium is measured using a thermal beam of metastable helium atoms excited to the 2 3P state using a 1.08-&mgr;m diode laser. The 2 3P1-to- 2 3P2 transition is driven by 2.29-GHz microwaves in a coaxial transmission line. Our result of 2 291 174.0+/-1.4 kHz is the most precise measurement of helium 2 3P fine structure. This measurement plays a key role in obtaining a new value for the fine-structure constant.     

Observation of fine structure in the 1s2s2p P-1s2p S transition of core-excited O V

We have measured the absolute wavelengths of the fine structure components of the 1s2s2p^{2 5}P-1s2p^{3 5}S transition in beryllium-like oxygen using the method of fast ion spectroscopy. These results represent the first measurement of fine structure in any core-excited 4-electron ion. We have also measured the lifetime of the metastable 1s2p^{3 5}S state. The structure and lifetime results are compared with recent relativistic MCHF calculations.     

类铍离子1s22s2p 3P1, 2 能级之间的磁偶极跃迁

用多组态Dirac-Fock和相对论组态相互作用的扩展优化能级方法,在计算中包含了Breit相互作用,真空极化,自能以及有限核质量修正,计算了核电荷数从Z=6到80的类铍离子等电子序列的1s22s2p 3P1, 2的精细结构能级,磁偶极跃迁几率和振子强度。结果与目前可靠的结果在其不确定度范围内符合得很好,另外也得到一些与其他早期理论计算不同的结果。     

QED and hyperfine splitting in the 2s1/2−2p3/2 X-ray transition in lithium-like Bi80+

The measurement of the Bi⁸⁰⁺ 2s_1/2−2p_3/2 transition energy is discussed. The measurement resolved the hyperfine splitting of the (1s²2s) F=4,5 ground configuration and allowed a determination of the Lamb shift contributions with a precision of about 9 × 10^-4 providing the most accurate test of QED in a high-Z ion to date. This revised version was published online in July 2006 with corrections to the Cover Date.     

Precise determination of the 2s(1/2)-2p(1/2) splitting in very heavy lithiumlike ions utilizing dielectronic recombination

The 2s(1/2)-2p(1/2) energy splittings DeltaE(L) of the lithiumlike ions 19779Au76+, 20882Pb79+, and 23892U89+ have been measured at the Experimental Storage Ring, utilizing low energy dielectronic recombination. The resonance energies in total 41 different 1s(2) 2p(1/2)nl(j(')) (n > or =20) autoionizing Rydberg states populated in the dielectronic capture process have been determined. The 2s(1/2)-->2p(1/2) excitation energies have been obtained by extrapolation of these resonance energies to the associated series limits n--> infinity. The combined analysis of the experimental data for all three ions yields DeltaE(L)=216.134(96) eV for Au76+, 230.650(81) eV for Pb79+, and 280.516(99) eV for U89+.     

Storage-ring measurement of the hyperfine induced 47Ti18+(2s2p 3P0 --> 2s2 1S0) transition rate

The hyperfine induced 2s2p (3)P(0) --> 2s(2) (1)S(0) transition rate A(HFI) in berylliumlike (47)Ti(18+) is measured. Resonant electron-ion recombination in a heavy-ion storage ring is employed to monitor the time dependent population of the (3)P(0) state. The experimental value A(HFI)=0.56(3) s(-1) is almost 60% larger than theoretically predicted.     

Radiative de-excitation of the 1s22s3 p 3P0 level in beryllium-like ions: A competition between an E2 and a two-electron one-photon E1 transition

I have performed a complete Multi-Configuration Dirac-Fock calculation of the radiative de-excitation of the 1s²2s3p³P₀ level in beryllium-like ions. Initial and final wave functions are fully optimized, and include valence and core polarization correlation (Coulomb and Magnetic). Non-orthogonality between initial and final state spin-orbitals is exactly accounted for. I show that the main mode of de-excitation of the 1s²2s3p³P₀ level at high Z is an E2 transition to the 1s²2s2p³P₂ and that a two-electron one-photon E1 transition to the 1s²2p^{2 3}P₁ plays an important role at low Z. The latter transition appears to be the difference of two large matrix elements which cancel almost exactly and thus has a very complicated Z dependence, which is studied in the present paper. This revised version was published online in August 2006 with corrections to the Cover Date.     

类铍离子磁四极M2 2s2 1S0—2s2p3P2 (Z=10—103)禁戒跃迁

利用全相对论多组态Dirac-Fock方法系统地计算了高离化类铍离子的磁四极M2 2s²¹S₀—2s2p³P₂ (Z=10—103)自旋禁戒跃迁的能级间隔、跃迁概率和振子强度，计算中考虑了重要核的有限体积效应，Breit修正和QED修正，所得结果和最近的实验数据以及理论值进行了比较，结果表明：高原子序数的高电荷离子(Z≥70)磁四极M2自旋禁戒跃迁几乎可以和中性原子的光学允许跃迁相比拟，不仅在天体等离子体中，在ICF和MCF高温激光等离子体中，磁四极自旋禁戒跃迁和其他自旋禁戒跃迁（磁偶极、电四极）一样不容忽视，在双电子复合、不透明度、自由程等理论计算中应该考虑其影响. 关键词： 磁四极M2 能级间隔 跃迁概率 振子强度     

类铍离子磁四极M2 2s2 1S0-2s2p 3 P2(Z=10-103)禁戒跃迁

利用全相对论多组态:Dirac-Fock方法系统地计算了高离化类铍离子的磁四极M2 2s2 1S0-2s2p3P2 (Z=10-103)自旋禁戒跃迁的能级间隔、跃迁概率和振子强度,计算中考虑了重要核的有限体积效应,Breit修正和QED修正,所得结果和最近的实验数据以及理论值进行了比较,结果表明:高原子序数的高电荷离子(Z≥70)磁四极M2自旋禁戒跃迁几乎可以和中性原子的光学允许跃迁相比拟,不仅在天体等离子体中,在ICF和MCF高温激光等离子体中,磁四极自旋禁戒跃迁和其他自旋禁戒跃迁(磁偶极、电四极)一样不容忽视,在双电子复合、不透明度、自由程等理论计算中应该考虑其影响.