Isotope shift studies in the first spectrum of dysprosium: confirmation of assignments to and new assignments to configuration

Isotope shifts (-) are reported for 221 spectral lines of the neutral dysprosium atom (Dy I) in the region 470-565 nm using a photoelectric recording Fabry-Perot spectrometer and highly enriched isotopic samples of and excited in liquid-nitrogen-cooled hollow-cathode lamps. Isotope shift data for 173 of these lines are being reported for the first time. Using the isotope shift data, term isotope shifts (-) have been evaluated for 99 even- and 68 odd-parity energy levels of Dy I. New values have been obtained for 24 odd and 36 even levels. These new values have enabled us to check some of the existing tentative assignments and also to suggest configuration assignments to a few unassigned energy levels. The earlier tentative assignments of 4 f10 5 d 6 p configuration to many high odd levels lying above have been presently confirmed. We could assign the 4f^95d6s6p configuration to 24 unassigned even levels. Received: 3 August 1998     

CuⅩⅧ离子谱线波长和跃迁概率的理论计算

用多组态HFR方法对CuⅩⅧ离子n=3complex组态能级结构进行了综合的分析与计算.在已 有实验工作的基础上，运用参数拟合方法获得了能级结构参数的最佳计算值，由这些参数值 预测计算了CuⅩⅧ离子n=3complex组态能级以及3s²—3s3p,3s3p—3p ²,3p²—3p3d,3s3d—3p3d,3p3d—3d²组态能级跃迁的谱线波 长，振子强度和跃迁概率. 关键词： CuⅩⅧ离子 原子能级 跃迁谱线波长 振子强度和跃迁概率     

Lifetime measurements for some levels in Be-like Cl XIV and S XIII

Lifetime measurements have been carried out for some low lying (n = 2) levels in the four-electron ions Cl XIV and S XIII using the beam-foil technique. Accurate oscillator strengths for the 2 s2 ¹ S - 2 s 2 p ¹ P o transition have been determined by the inclusion of prominent cascades in the analysis. Lifetimes of the levels of the 2 p2 ³ P j multiplet have also been measured for both ions. The results are compared with theoretical predictions and earlier measurements. Received: 29 October 1997 / Revised: 10 February 1998 / Accepted: 5 March 1998     

Effective Hubbard model for Zn-doped CuO2 plane

In the framework of the cell-perturbation method for the original p-d model an effective two-band Hubbard model for the CuO₂ plane with Zn impurities is derived. Zn impurities are modelled by Wannir oxygen one-hole states at vacant Cu sites. The model is based on the results of band structure calculations carried out within the local-density approximation. Further reduction to an extended t-J model shows a large ferromagnetic superexchange interaction between the Cu spin with the nearest virtual oxygen spin in the Zn cell. Received 17 November 1998     

The shapes of Auger decay lines in photoelectron satellite spectra

The theory of the shapes of Auger decay lines of satellite two-hole-one particle states accompanying photoionization based on the Green's function method is developed. The lineshapes of Auger decay of satellite states [2 s 2 p ]( ^1,3 P )3 s ( ² P ), [2 s 2 p ]( ¹ P )4 s ( ² P ) and [3 s 3 p ]( ³ P )4 s ( ² P ) in valence p-photoelectron spectra of Ne and Ar atoms are calculated (hole states are indicated by square brackets throughout). It is shown that in some cases the Auger lineshapes reproduce the shape of the photoelectron satellite line, but in other cases Auger line may be narrower then the photoelectron line and may have opposite direction of asymmetry. The theoretical results are in agreement with experimental low-energy Auger spectra. Received: 25 May 1998 / Accepted: 2 October 1998     

Radiative lifetime and oscillator strength determination in Mg-like potassium (K VIII)

Theoretical transition probabilities have been obtained for 54 n = 3 transitions depopulating the 3s3p ¹P^o, 3p^{2 3}P, ¹D, ¹S, 3s3d ¹D, ³D and 3p3d ³P^o, ³D^o, ³F^o, ¹F^o, ¹D^o, ¹P^o levels, including 14 transitions not yet observed. Some of these predictions have been compared with experimental lifetimes obtained by beam-foil spectroscopy for four n = 3 levels of K⁷⁺. An excellent agreement is observed between theory and experiment for all the levels. Received 23 January 2002 / Received in final form 23 April 2002 Published online 19 July 2002     

Quantum theory of the magneto-optical effect induced by Ni ions in barium ferrites

To reveal the physical origin of the giant magneto-optical enhancement of Ni²⁺ ions in barium ferrite, quantitative calculations of the contributions of both the intra-ionic electric dipole transition between the 3d⁸ and 3d^{7 4p} configurations of the Ni²⁺ ions and the intra-ionic electric dipole transition induced by odd-parity crystal field terms are presented. It is deduced that the transition is important in the origin of the considered magneto-optical enhancement. The most important factor is the Ni-Fe superexchange interaction; since it is strong enough, the Faraday rotation produced by the Ni²⁺ ions is large though the energy difference between the 3d⁸ and 3 d7 4 p configurations is large. It is demonstrated that though the intra-ionic electric dipole transition does produce Faraday rotation peaks in the visible range, their magnitude is too small to explain the observed Faraday rotation. The effect of the spin-orbit interaction on the Faraday rotation is analysed. The spin-orbit interaction of the ground configuration plays a very important role in the occurrence of Faraday effects, but the Faraday rotation does not increase linearly with the strength of the spin-orbit coupling. On the contrary, the spin-orbit interaction of the excited configuration has almost no effect on the Faraday rotation. It is shown that the mixing of the different multiplets of the ground term induced by the crystal field has a great influence on the magneto-optical properties. Received 7 January 1998     

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     

The linkage between macroscopic gettering mechanisms and electronic configuration of 3d-elements in p/p+ epitaxial silicon wafers

We have measured the gettering efficiencies for Cr, Mn, Fe, Co, Ni and Cu in p/p+ epitaxial wafers. The gettering test started with a reproducible spin-on contamination on the front side of the wafers in the 10¹²–10¹⁴ atoms/cm² range, followed by thermal treatment to redistribute the metallic impurities in the wafer. The gettering efficiencies were measured by a novel wet chemical stratigraphic etching technique in combination with inductively-coupled plasma mass spectrometry. The residual bulk metal contamination was also measured by this method. This procedure led to global distributions of the 3d elements on the wafer’s front side, in the bulk of the wafer and on the wafer’s back side. Recovery rates were found to be 34%, 2.3%, 100%, 85%, 100% and 100% for Cr, Mn, Fe, Co, Ni and Cu, respectively. An impurity segregation effect in the wafer bulk was measured for Cu (100%) and Cr (34%), while no detectable segregation-induced gettering mechanisms were detected for the other elements in the applied concentration range. The segregation-induced gettering mechanisms were interpreted from the electronic structure of the metallic impurities. For segregation gettering by increased solubility in p+ silicon, the metallic species must form donors. Only Cu⁺ (3d ¹⁰) and Cr⁺ (3d ⁵) can form singly positively charged species that exhibit a spherical electronic distribution. It is well known from spinell structures that 3d ¹⁰ and, to a smaller extent 3d ⁵, are stable configurations in tetrahedral structures like the silicon lattice. Thus, we link the segregation-induced gettering mechanism in p/p+ epitaxial wafer to the electronic configuration of the 3d elements. Received: 19 January 2001 / Accepted: 31 January 2001 / Published online: 20 June 2001     

Dynamics of isolated twin boundary in (TMTSF)

Intermittent and irregular motion of isolated twin boundary (kink) in organic crystal (TMTSF)₂PF₆ was studied at room temperature. Both the local velocity and the time of intermission are determined not only by external stress and temperature but also by the time (t w) elapsed after the backward passage and before the following forward one. When the kink moves after longer t w, its velocity becomes smaller and the time of intermission longer. Both tend to saturate for t w longer than 10² s. This result indicates that some disorder is induced in the lattice by the backward motion and it is relaxed during t w. We also found that the effect of the backward motion of one kink on its following motion is equivalent quantitatively to that of the forward motion of the pair-created counterpart. Received: 14 April 1998 / Received in final form and Accepted: 1st September 1998     

Level lifetimes in 3p and 3d configurations of Fe XII

Transitions between the five fine-structure levels in the 3s ²3p ³ ground configuration of Fe XII (P-like) are of interest in astrophysics and terrestrial plasma diagnostics. The decay rates give rise to level lifetimes in the millisecond range, which have been measured recently at a heavy-ion storage ring. While most of the 3s ²3p ²3d levels are short-lived, two of these levels have no E1 decay channels and may also have millisecond lifetimes. We present HFR and MCDF calculations of the E1, M1, E2 and M2 transition rates between the 3s ²3p ³, 3s3p⁴ and 3s ²3p ²3d levels and compare the lifetime results to most recent experimental data as well as to other predictions. Received 2 October 2001 / Received in final form 22 January 2002 Published online 28 June 2002     

Nuclear fusion in charge-asymmetric muonic molecules

Nuclear fusion reactions in hydrogen-lithium muonic molecules, (where h=p,d,t) are considered and fusion rates from rotational states J=0 of the molecules are presented. Results obtained depend on the isotopic composition of the molecules and range between and . The upper limit for fusion rates from rotational states J=0 of hydrogen-helium muonic molecules, and , equal , is also found. Received: 4 December 1997 / Revised: 30 April 1998 / Accepted: 7 May 1998     

Reanalysis and semi-empirical predictions of the hyperfine structure of in the model space

On the basis of most of the earlier hyperfine-structure (hfs) experimental results, the hfs of the atomic zirconium has been reanalyzed by the simultaneous parameterization of the one- and two-body interactions for the model space (4 d + 5 s ) ⁴ . The values of the one- and two-body hfs parameters have been determined and the nuclear quadrupole moment, free of Sternheimer corrections up to second order, has been evaluated. Moreover, the values of the magnetic-dipole A and the electric-quadrupole B constants for all known levels of this model space have been predicted. Received: 22 December 1997 / Revised: 15 May 1998 / Accepted: 1 July 1998     

Investigations on the soft-mode mechanism of the ferroelectric phase transition in

Dielectric and Raman spectroscopic measurements have been performed to investigate the ferroelectric phase transition in . Single crystals were grown by the zone melting method. The frequency dependence of the dielectric permittivity from 1 MHz to 1 GHz has been studied in a temperature range between 265 and 285 K. A Debye like dielectric dispersion was found, showing a critical slowing down around K. Polarized Raman spectra have been taken between 220 and 310 K. Two softening modes have been found, one of A- and another one of B / B g-symmetry. The phase transition mechanism in can be classified as partially order-disorder and partially displacive, confirming former structural results. It resembles strongly that of monoclinic . Received: 7 April 1998 / Revised: 5 June 1998 / Accepted: 16 June 1998     

High spin state of Mn in an ideal monolayer on Ag(001)

We studied the magnetic properties of ultra-thin Mn films deposited on Ag (001) held at 80 K with soft X-ray absorption and magnetic circular dichroism. The observed shape and branching ratio of the Mn 2p absorption edge as a function of Mn coverage demonstrate that, up to , the Mn adopts a stable high spin state similar to the Mn atom Hund's rule ⁶ S _5/2 ground state. Above this coverage a rapid transition from localized high spin to itinerant low spin behavior of the Mn 3d electrons is evidenced. Magnetic circular dichroism shows no sign of long range ferromagnetic order in these films at 80 K. The data, first confirm the large atomic-like local magnetic moment, and second are in line with the in-plane antiferromagnetic order, reported recently (Phys. Rev. B 57, 1141 (1998)), for Mn in the nearly ideal on-top Mn monolayer formed by 0.9 ML deposited at 80 K. Received: 4 May 1998     

autoionizing levels in Ca: laser optogalvanic spectroscopy and theoretical analysis

We report the even parity J =4,5 autoionizing spectra of calcium below the 3d threshold, investigated by two-step laser excitation from the 3d4s metastables through the 3d4p , intermediate states and subsequent optogalvanic detection. The 3d4s states are populated by electronic collisions in a d.c. glow discharge sustained in a Ca heat-pipe. More than a hundred resonant transitions have been measured with an accuracy of for the narrow ones using standard laser calibration techniques. The high lying levels are assigned to all expected autoionizing series. Moreover, some levels are observed. The theoretical interpretation is achieved by a combination of the nearly ab initio eigenchannel R-matrix and multichannel quantum-defect (MQDT) methods as well as by an empirical determination of the MQDT parameters in the phase-shifted formulation. Theoretical energy level positions and excitation profiles are compared with the experimental data confirming the identification of the observed structures. Strong mixing between series is found, while the ones do not couple with the series. Further insight into the strong channel mixing in the studied energy range is provided by a comprehensive review of the excitation profiles in the vicinity of the 4p5p perturber as obtained from a number of intermediate levels used in the present and in earlier experiments. Systematic electron correlation trends for series of , and are discussed. Received: 20 November 1997 / Accepted: 15 January 1998     

Doppler limited laser spectroscopy on hafnium lines. Part II: Hyperfine structure of odd-parity levels

The hyperfine structure of selected odd-parity levels of the configurations 5d6s ^26p and 5d ^26s6p of I was studied in 10 lines lying in the red spectral region. Hyperfine spectra were obtained by the method of laser induced fluorescence in the plasma of a liquid nitrogen cooled hollow cathode discharge. The observed hyperfine structure constants A and B, together with results from earlier studies were analyzed by means of a parametric method. The interpretation has been carried out based on a refined multiconfigurational fine structure calculation including the main Rydberg series configurations mutually interacting. The set of fine structure parameters as well as the leading eigenvector percentages of levels relevant for this paper are given. The following single electron hfs parameters were deduced for : , ,, for the lowest configuration. Received: 16 November 1998 / Received in final form: 5 February 1999     

Electron excitation of neutral and ionic levels in Townsend discharges of argon at high E/N

We have measured the emission coefficients of the 3p levels of ArI: 3p₁, 3p₅, 3p₆, 3p₇, 3p₈, and 3p₁₀. The data for the 3p₅, 3p₆, 3p₇, 3p₈ and 3p₁₀ levels were converted to excitation coefficients by using quenching coefficients from the literature. Measurements were performed in the range of E/N between to above except for the 3p₇ level where measurements were done only up to . The data for the emission coefficients for Ar II levels include two 4p' levels with terms ² P ⁰ _1/2 and ² F ⁰ _7/2, and three 4p levels with terms ² P ⁰ _1/2, ⁴ P ⁰ _5/2 and ² D ⁰ _5/2. The measurements for the ionic levels were done for E/N above up to nearly . The absolute values of the coefficients were obtained from the intensity of the light emitted at the anode in the parallel plate self-sustained Townsend argon discharges. For low E/N the apparent emission coefficients (i.e. the normalized spatial profile of emission) for both neutral and ionic levels increase exponentially in almost the entire discharge gap. At about the exponentially increasing signal was obtained only near the anode, while at the spatial dependence was flat throughout the electrode gap. Received: 18 January 1999 / Received in final form: 12 April 1999     

Radiative lifetime and oscillator strength determinations in potassium ions (K V, K VI and K VII)

Oscillator strengths have been calculated for the transitions depopulating levels of the 3s²3p³, 3s3p⁴ configurations of K V, of the 3s²3p², 3s3p³ configurations of K VI and of the 3s²3p, 3s3p², 3p³ and 3s3p3d configurations of K VII. A multiconfiguration Dirac-Fock method, incorporating the relativistic two-body Breit interaction and quantum electrodynamics corrections due to self-energy and vacuum polarization, has been used for the calculations. The reliability of this approach has been tested by comparison with relativistic Hartree-Fock calculations and also with some experimental measurements performed by beam-foil spectroscopy at a beam energy of 1.7 MeV.     

Photoionization cross-section measurements from the 2p, 3d and 3s excited states of lithium

The photoionization cross-sections from the 2p²P_{1/2, 3/2}, 3d²D_{3/2, 5/2} and 3s²S_1/2 excited states of lithium have been measured at different ionizing laser wavelengths, above the first ionization threshold. The experiments are performed by using a thermionic diode working in the space charge limited mode and the cross-sections are measured by employing the saturation technique. By changing the ionization photon energy, a smooth frequency dependence of the cross-sections has been observed for the 2p and 3d states. The cross-section from the 3s excited state has been measured at a single photon energy. The measured values of the photoionization cross are compared with the available data.