Photoelectron and photoion spectroscopy on atomic Lu in the region of the 5p excitation

The resonances of atomic Lu have been investigated by photoelectron and photoion spectroscopy using monochromatized synchrotron radiation in the vacuum ultraviolet energy region. The total photoion yield has been compared to calculations in which the extended Fano theory (Mies formalism) and the Hartree-Fock method were applied. The resonance structure is dominated by the spin-orbit splitting of the 5p core hole. In the photoion yield spectra of singly and doubly charged ions a high fraction of Lu²⁺ ions has been found in the region of the 5p ^-1 (² P _1/2 )nd resonances. Photoelectron spectra, recorded in this resonance region, have been investigated with respect to deexcitation channels connected with Lu²⁺ ions. The 5p ^-1 (² P _1/2 )nd resonances predominantly autoionize by spin-flip into states, which decay in the second step into Lu²⁺ final ionic states. Received: 2 September 1998 / Accepted: 17 September 1998     

Lineshape of Ne 1s photoionization satellite [1s2s](3S)3s and its valence Auger decay spectrum

Lineshape of Ne1s photoionization satellite $\text{[1s2s](}{}^3\text{S)3s(}{}^2\text{S)}$ and lineshapes of corresponding low-energy Auger spectra are calculated using the Many-Body Perturbation Theory. The results obtained reproduce the experimentally observed asymmetrical lineshape of photoelectron satellite and its intensity.     

Investigation of auto-ionizing states in xenon by resonantly enhanced multi-photon ionization

We have examined the autoionization spectrum of xenon by resonantly enhanced three-photon ionization (2 + 1 REMPI) involving intermediate states 5p ⁵6p[J = 0, 2]. The properties of the observed autoionization resonances change significantly with the choice of the intermediate state. For ionization via an intermediate state with predominantly 5p ⁵(²P_3/2) core character, a strong continuum with embedded window-type 5p ⁵(²P _1/2)nd'-autoionization resonances is observed. For intermediate states, predominantly with 5p ⁵(²P_1/2) core character, both 5p ⁵(²P _1/2)nd'- as well as 5p ⁵(²P _1/2)ns'-resonances are present in the spectrum as overlapping, nearly symmetric peaks on a rather weak continuum. Calculations confirm the significant dependence of the spectral lineshapes upon the excitation pathway to the autoionizing state. The ionization data are compared with spectra obtained by monitoring third-harmonic generation via autoionizing states without resonant excitation of intermediate states. These spectra also exhibit the signature of both the nd'- and ns'-resonances. Received 30 September 2002 Published online 28 January 2003 RID="a" ID="a"Permanent address: Rostov State University of Transport Communication, 344038, Rostov-on-Don, Russia. RID="b" ID="b"e-mail: halfmann@physik.uni-kl.de     

Ne原子的1s光电离及其Auger衰变过程的理论研究

利用基于多组态Dirac-Fock理论方法的研究原子结构和性质的程序GRASP92和RATIP以及最新发展的研究光电离和辐射复合过程的程序RERR06,研究了光子能量为947.9 eV时Ne原子的1s光电子谱及其相应的Auger衰变过程.所得结果与其他的理论结果和实验结果符合得很好.通过分析光电离伴随态Ne⁺1s^-12p^-1（^1,3Ｐ）3p的Auger衰变过程可知：3p旁观的Auger跃迁是主要的衰变机制,Ne⁺1s^-12p^-1（¹Ｐ）3p的Auger强度整体上大于Ne⁺1s^-12p^-1（³Ｐ）3p的Auger强度.同时,也预言了光电离伴随态Ne⁺1s^-12p^-1（^1,3Ｐ）3p产生的Ne⁺,Ne²⁺和Ne³⁺末电离态离子的相对丰度分别为0.02,0.58和0.41. 关键词： 光电离 Auger衰变 多组态Dirac-Fock方法     

Sextet levels in the phosphorus-like ion Cu

Delayed spectra of foil-excited fast Cu ions have been studied to find a number of 3s3p⁴, 3 s2 3 p2 3 d and 3s3p^33d levels in the P-like ion Cu¹⁴⁺ (spectrum Cu XV). Among these are 3 s 3 p3 3 d ⁶ D levels, which have never been observed before, although they are the lowest excited states that have the same parity as the ground configuration. The investigation combined theory and experiment. The calculations used the Cowan code with semi-empirically scaled parameters and extensive MCDF computations. Received: 14 April 1998 / Accepted: 18 April 1998     

Observation of the radiative 2s02p6−2s12p5 transition in NeIII

Ion impact excited spectra of Ne contain a line at 52.82 nm which has been identified as resulting from the decay of double 2s vacancies in NeIII via the transition 2s⁰2p⁶(¹S₀)?2s¹2p⁵(¹P₁).     

Near-IR laser inelastic electronic light scattering spectroscopy on transitions between ground and excited states of acceptor centers in GaAs and InP crystals

We report the development of a method for recording the low-temperature (T=6 K) near-IR inelastic light scattering spectra and the observation of electronic scattering on the transitions 1s _3/2(Γ₈) → 2s _3/2(Γ₈) between the ground and excited states of different shallow acceptor centers in a n-type semi-insulating crystal si-GaAs (n=1.0 × 10⁸ cm⁻³) and in a doped p-InP crystal (p=3.6×10¹⁷ cm⁻³). Moreover, a new line, associated with the transition 1s _3/2(Γ ₈) → 2p _3/2(Γ₈) and due to a dielectric local mode, recorded for the first time in the spectra of narrow-gap semiconductors, was found in the residual-frequency band in the p-InP spectrum between TO(Γ) and LO (Γ) phonons. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 5, 334–339 (10 March 1998)     

Triple differential cross section of electron impact ionisation of Na(3s, 3p, 3d)

The fivefold differential cross section (5DCS) of the ionisation by electron impact of atomic sodium is determined theoretically for its fundamental 3s(² S) state and the excited 3p(² P) and 3d(² D) states by a procedure which employs in the transition matrix element of the first order Born approximation, the correlated double continuum (3C) wave function. This permits us to determine the statistical M-state population and the orientation and alignment tensors in (e,2e) detection. It is also shown that, the use of Gamow correlation term, in the independent particle (2C) model, reproduces, only in some situations, the shape of the angular distribution of the 5DCS obtained by the (3C) wave function. Received: 17 November 1997 / Received in final form: 16 March 1998 / Accepted: 21 March 1998     

Two-step excitation of an auto-ionized state of the Ba atom associated with two-photon excitation of an intermediate state

An experimental and theoretical study is performed of the angular photoelectron distribution for three-photon ionization of Ba atoms through the 2ω-excited intermediate state 6p ²(¹ S ₀) and the auto-ionized state 6p8s(³ P ₁). Rotation of the polarization plane of dye-laser radiation allowed us to investigate the photoelectron angular distribution. Electrons were counted with the help of a time-of-flight electron spectrometer. The density-matrix formalism is used to obtain expressions for the angular dependence of the differential ionization probability. Possible experiments are discussed. Zh. éksp. Teor. Fiz. 113, 834–840 (March 1998)     

On resonance processes in near-threshold excitation of the resonance lines of a Zn+ ion in electron-ion collisions

The excitation of the components of the 4p ² P ₁ ^2,3/2/0 resonance doublet of the Zn⁺ ion by monoenergetic electrons in the interval 4–10 eV is investigated by a spectroscopic method in crossed beams. Resonances are found in the energy dependences below and above the excitation thresholds of resonance lines. The subthreshold resonances are satellite of the lines investigated and are excited in the process of dielectronic recombination. The main competing process here is the electronic decay of autoionizing states, which is manifested in a resonance excitation of the ions starting at the thresholds for the excitation of the levels. Autoionizing states lying between the levels of the doublet splitting of the 4p ² P ₁ ^2,3/2/0 state decay to the 4p ² P ₁ ^2/0 level in a Koster-Kronig process. Above the excitation energy of the 4p ² P ₃ ^2/0 level the the dominant contribution to resonance excitation is from autoionizing states with configurations 3d ⁹(² D _5/2,3/2)4s ² np,(n−1)f. Pis’ma Zh. éksp. Teor. Fiz. 68, No. 8, 614–617 (25 October 1998)     

Auger transitions in Li-like and Be-like ions

Measurements of the Auger decay of beam-foil excited Be II and Be I levels are reported along with a proposed assignment of the experimental spectra. The Li I, Be II and Be III (1s2s²)²S → (1s²2s)²S Auger transitions as presented in this letter represents the first observation of such states in positive ions with Z?5.     

Cusp satellite bands in the spectrum of molecule

We report measurements and a theoretical explanation of the cusp-shaped satellite bands in the blue wing of the cesium D₂ resonance line which have been observed for the first time. The bands are identified as transitions where the upper state dissociates into the 6 ²P _3/2 + 6 ² S _1/2 atomic asymptote. The experiment has been performed using a standard absorption setup, computer controlled data acquisition and computer data processing. We have shown that the peculiar shape of the difference-potential curve is solely responsible for the spectrum containing the cusp-shaped satellite bands. The appearance of these satellite bands has been discussed and explained relating the theory of satellite bands to the catastrophe theory. The shape of the line wing and of the satellite bands have been calculated using the Fourier transform technique. To ensure a more stringent comparison between the experimental and the theoretical spectrum, we have analyzed and compared the derivatives of the measured and the calculated satellite band shape. On the contrary to the customary direct comparison between the measured and the calculated absorption coefficient, the derivative clearly shows all differences and resemblances between satellite band profiles. The degree of coincidence of the experimentally observed and the theoretically calculated satellite band shape can be used as an ultimate check on the assessment of the quality of potential-energy curves involved in the formation of satellite bands. Received: 1 October 1997 / Revised: 14 January 1998 / Accepted: 24 February 1998     

Line emission and alignment effects in state selective electron transfer in He2+-Li(2s, 2pΣ, 2pΠ) collisions

Classical Trajectory Monte-Carlo (CTMC) method has been used to investigate state selective electron capture by He²⁺ ions colliding with Li(2s) and Li(2p) in as well as alignments in the energy range 1-15 keV/amu. He⁺(4l) electron capture, line emission [He II(n = 4 3)] cross-sections and alignment parameters have been calculated and analyzed in the light of the available results. The undulatory structure of the capture and emission cross-sections have been explained qualitatively in terms of a quasi-molecular ion formation. Projectile impact energy and spatial overlap play crucial role in determining the alignment effects. Received 3 July 1998 and Received in final form 3 June 1999     

Many-electron character of Rydberg series converging to the ionization thresholds of the 4<Emphasis Type="Italic">p</Emphasis><Superscript>4</Superscript>5<Emphasis Type="Italic">s</Emphasis> states of KrII

The photoionization cross sections of the 4p shell and the 4s main level and 4p ⁴(³ P) 5s ⁴ P _{5/2, 3/2} satellite subvalence levels of KrII have been calculated in the 4s-near-threshold range of excitation energies from 28.48 to 28.70 eV. The calculation takes into account the core relaxation by the methods of the theory of non-orthogonal orbitals, the interaction between resonant states through autoionization channels by solving the complex secular equation, and the interaction between the channels of the continuous spectrum in all orders of the perturbation theory by the K-matrix method. Good quantitative agreement between the energy-integrated theoretical and experimental photoionization cross sections for the satellite levels has been obtained for the first time. It is shown that only simultaneous consideration of the above-mentioned effects leads to such agreement. The resonant structure of the photoionization cross sections in this excitation energy range is related to the autoionization decay of the 4p ⁴5s(⁴ P _1/2)np and 4p ⁴5s(² P _3/2)np Rydberg series. The specificity of this process is that both series manifest themselves not independently but owing to their strong electrostatic interaction with the prominent 4p ⁴(¹ D)5s ² D _5/2 6p _3/2 resonance, which lies in this excitation energy range.     

Fine structure and isotope shift of the 3s4d 3 D-3s3p 3 P, 3s5d 3 D-3s3p 3 P and 3p 2 3 P-3s3p 3 P Transitions of MgI

Summary We report the measurements of the³ D(3s4d)-³ P(3s3p)³ D(3s5d)-³ P(3s3p), and³ P(3p ²)-³ P(3s3p) transition frequency of MgI, the fine-structure separation and isotope shift between²⁴Mg and²⁶Mg. The measurements have been performed in a metastable atomic beam; a good agreement is found for data already existing in the literature. The accuracy of the measurements reported in this paper is mainly limited by the Doppler broadening of theI ₂ transitions used as a reference and by the precision in the knowledge of the related wavelengths.     

Energies, Auger and radiative probabilities of the doubly-excited 1s23l3l′ states for Be-like neon

Energy levels, Auger decay and radiative transition rates of the doubly-excited 1s ²3l3l′ states for Be-like neon are calculated using relativistic Multiconfiguration Dirac-Fock (MCDF) method. Electron correlation and relaxation effects are taken into account. The magnitude of Auger rates for the 35 doubly-excited states and their decay channels are discussed. Present calculated values are in agreement with the latest experimental electron spectra as well as other theoretical results.     

High resolution measurement and MQDT analysis of the 5d<Superscript>9</Superscript> 6s<Superscript>2</Superscript> np,nf (J = 1) autoionizing resonances of mercury

We report new high resolution photoabsorption measurements of the 5d-subshell excitation spectra of mercury using a 3-meter normal incidence spectrograph equipped with a 6000 line/mm holographic grating and synchrotron radiation emitted by the Bonn 2.5 GeV electron accelerator as the background source of continuum. The observed spectra reveal autoionizing resonances attached to the 5d⁹(²D_5/2)6s² and 5d⁹(²D_3/2)6s² parent ion levels of mercury. We have analysed the line shapes of the lower members of the 5d⁹6s² np and nf J = 1 autoionizing resonances using the phase shifted formulation of the MQDT and extracted the interaction parameters.     

X-ray photoelectron spectra and structure of iron polynuclear complexes

Iron trimethylacetate complexes with different ligands have been investigated by X-ray photoelectron spectroscopy (XPS). The Fe 2p, Fe 3p, C 1s, O 1s, and N 1s spectra obtained at successive replacement of the Fe-O coordination bonds with Fe-N bonds have been analyzed. A satellite component is found in the spectra of iron trimethylacetate complexes, which is indicative of the high-spin state of Fe^II and Fe^III iron atoms. The XPS data made it possible to determine the degree of covalence of the metal-ligand bonding and reveal two nonequivalent states for iron atoms.     

F3+和Ne4+离子的光电离截面的理论计算

利用R矩阵方法计算了F³⁺和Ne⁴⁺离子的基态2s²2p²(³P)和激发态2s²2p² (¹D,¹S),2s2p³ (⁵S^o)的分波光电离截面、总光电离截面,分析辨认出了这些离子在自光电离过 关键词： 3+离子和Ne⁴⁺离子')" href="#">F³⁺离子和Ne⁴⁺离子 光电离 自电离共振 R矩阵')" href="#">R矩阵     

Ionization of barium through a coherent excitation of two bound intermediate states

We have investigated theoretically the asymmetrical photoionization yields into the 6s _1/2, 5d _3/2 and 5d _5/2 continuum channels of atomic barium observed by Wang, Chen and Elliott [Phys. Rev. Lett. 77, 2416 (1996)] in the study of coherent control through two-color resonant interfering paths. The atomic parameters obtained from a theoretical approach based on a combination of jj-coupled eigenchannel R-matrix and Multichannel Quantum Defect Theory are used to analyze the photoionization spectra from the and 6s7p states with polarized light beams. The studied energy range includes the 6p7p autoionizing resonances. The dynamics of the two-color photoionization is governed by the coherent excitation of the 6s6p and intermediate states. This excitation is described as an adiabatic process in the rotating wave approximation. The influence of the radiative decay, spatial distribution of the intensities of the laser beams and hyperfine interaction is discussed. Received 28 September 1999