Laser-induced fluorescence line narrowing in cobalt I

Laser-Induced Fluorescence Line Narrowing (LIFLN) measurements of hyperfine structure splittings performed on the cobalt I transition sequence3d ⁸4s a ² P _1/23d ⁷4s4p z ²4D _3/2 ⁰ 3d ⁸4s b ⁴ F _3/2are presented. The hyperfine coupling constants of theb ⁴ F _3/2 level were determined to beA = 302.8(1.9) MHz andB = – 81.6(18.2) MHz and are compared with results of both experimental and theoretical studies reported by other authors.     

Molecular dissociative sequential excitation and ionization of strontium vapor

We report new measurements on laser-assisted molecular dissociative sequential excitation and ionization spectra of strontium vapor. A single Nd:YAG pumped dye laser in conjunction with an atomic beam apparatus have been used to investigate the even parity 5snd ^3,1 D ₂ Rydberg series resulting from the 5s5p ¹ P ₁ resonance level. The relative intensities changes among the 5snd ³ D ₂ and ¹ D ₂ Rydberg series are attributed to the interactions with the 4d6s ^1,3 D ₂ perturbers, respectively. The interchannel interactions between the 5snd ¹ D ₂ series and the 4d6s ¹ D ₂ level and among the 5snd ³ D _1,2,3 series and the 4d6s ³ D _1,2,3 intruders have been separately parameterized using the two-channel quantum defect theory. Received: 10 September 1998 / Received in final form: 16 December 1998     

Gas phase high temperature photoelectron spectroscopy: an investigation of the transition metals scandium and vanadium

The He(I) photoelectron spectra of atomic scandium and vanadium have been recorded in the gas-phase. For scandium two bands associated with a (4s)^?1 ionization and one band associated with a (3d)^?1 ionization of the neutral atom have been observed. Measurement of their relative intensities allows the σ_3d:σ_4s photoionization cross-section ratio in atomic scandium to be estimated as 57.1 ± 9.0. In the atomic vanadium spectrum, six bands were seen. Four of these correspond to (3d)^?1 and (4s)^?1 ionizations of the ground state of the neutral atom, the V a⁴F state, whereas two bands correspond to (3d)^?1 ionizations of an excited state, the V a₆D state, which is approximately 2100 cm^?1 above the ground state. Measurement of the intensities of bands arising from the V a₄F state allows σ_3d:σ_4s to be estimated as 29.8 ± 2.5 for vanadium. Spectra of vanadium have been recorded with both single- and multi-detector photoelectron spectrometers. Comparison of the data acquisition rates obtained with both spectrometers demonstrates the advantage of using a multidetector instrument in high temperature photoelectron spectroscopy.     

Hyperfine structure in the atomic spectrum of niobium

A parametric analysis of the fine and the hyperfine structure for the three even configurations 4d^45s, 4d ⁴5s ² and 4d⁵ has been performed. Effective one-electron parameters a _nl ^kskl(k _s k _l = 01, 12 and 10) and b _nl ⁰² were determined for these three configurations. Extremely large ratios a _4d ¹⁰/a _4d ⁰¹ were found. Theoretical predictions for the hyperfine structure constants A and B for all levels of the configurations 4d^45s, 4d ⁴5s ² and 4d⁵ have been determined from experimental data. Additionally, the fine and hyperfine structure for the two energetically high lying even configurations 4d^46s and 4d^35s6s are discussed. The results presented here call into doubt the existence of the fine structure levels 4d ³5s6s ⁶ F _11/2 at an energy of 39 408.88 cm^-1 and 4d ³5s5p ⁶ G _13/2 at 18 876.46 cm^-1 given in the Moore tables.     

Two-color three-photon resonant excitation spectrum of strontium in the autoionization region

We report new studies of the odd parity autoionizing Rydberg series of strontium attached to the 4d( ² D _{3/2, 5/2}) ionic limits possessing J = 1-3 based on the two-color three photon resonant excitation technique in conjunction with an atomic beam apparatus. Using the 4d ²³ P ₀ intermediate levels, we have been able to record the autoionizing Rydberg series of J = 1 whereas, from the 4d ²³ P ₂ intermediate level the series of Rydberg levels possessing J = 1, 2 and 3 have been observed. The level assignments and the line shapes simulations of the autoionizing resonances have been made using the multichannel quantum defect theory. Received 21 November 2001 / Received in final form 2 May 2002 Published online 19 July 2002     

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     

NEW AUTOIONIZING STATES NEAR THE FIRST IONIZATION LIMIT OF RARE EARTH ELEMENT Dy

This paper describes the investigation of autoionizing states near the first ionization limit of rare-earth element Dy. The 62, 51, 97 and 25 new autoionizing states resulting from the states of 4f¹⁰(⁵I₈)6s6p(³P⁰₂)³I⁰₇, 4f⁹ (⁶H⁰)5d²(³F)(⁸G⁰)6s⁹G⁰₇, 4f⁹(⁶F⁰)5d6s^{2 7}H⁰₇ and 4f⁹5d6s^{2 7}K⁰₇, respectively, were found by using a laser resonance ionization time-of-flight mass spectrometer (LRI-TOFMS), The photoionization efficiencies for different channels were compared with each other. In addition, the Shore-Fano parameters of autoionizing states were determined by a nonlinear fitting program.     

Laser-rf double-resonance hyperfine structure measurements of the metastable 3d 4s 1 D 2 state of43Ca

The hyperfine structure of the (3(d 4s)¹ D ₂metastable state of⁴³Ca has been measured using theABMR-LIRF method (atomic beam magnetic resonance, detected by laser induced resonance fluorescence). The measurements yielded for the magnetic dipole and electric quadrupole constantsA=?17.650(2) MHz andB=?4.642(12) MHz, respectively. From the measuredB factor the spectroscopic electric quadrupole moment (uncorrected for shielding effects) has been calculated to beQ(⁴³Ca)=?0.062(12) barn. In addition, isotope shifts in the lines (3d 4s)¹ D ₂(3d 4p)¹ F ₃ ⁰ and (3d 4s)¹ D ₂(4s 5p)¹ p ₁ ⁰ for the stable calcium isotopes have been obtained by high resolution laser spectroscopy.     

Step-wise laser excitation of the 4snf 3F Rydberg states of neutral zinc

The new experimental results on the effective quantum numbers and term energies of the highly excited odd-parity 4s4d ³D_1,2,3 →4snf ³F_2,3,4 Rydberg transitions of zinc have been presented. The experiment was performed using the three dye lasers simultaneously pumped by the second harmonic (532?nm) of the Q-switched Nd:YAG laser. The new observation includes the 4snf ³F₃ (12?≤n?≤?50) series excited from the 4s4d ³D₂ intermediate level. In addition, the 4snf ³F₂ (12?≤n?≤?28) and 4snf³F₄ (12?≤n?≤?33) series are observed from the thermally populated 4s4d ³D_1,3 fine structure components. The ionization potential of zinc has been determined from the unperturbed 4snf ³F₃ series as 75769.31?±?0.15?cm^?1, which is in excellent agreement with the previously reported value.     

Hyperfine structure of nine levels in two configurations of93Nb

The hyperfine structure of the two multiplets 4d ⁴5s ⁶ D and 4d ³5s ^{2 4} F of⁹³Nb has been studied by the atomic-beam magnetic-resonance method. After applying corrections due to effects of off-diagonal hyperfine and Zeeman interactions the hyperfine interaction constantsA andB and the electrong factors g_J are determined for all nine levels of the two multiplets.     

Calculation of the Hyperfinestructure and gJ-Values of the 3d 4s 4p-Configuration of Scandium

Wave functions for the 3d 4s 4p, 3d² 4p and 4s² 4p configurations of ScI are calculated, taking into account departures from SL-coupling and configuration interaction and on fitting the radial integrals to the experimental fine structure energies. Using these wave functions g J -values are derived. The intermediate coupled hfs matrix elements of the 3d 4s 4p configuration are reduced to the unknown electron coupling constants a_s, a_p and a_d and calculated on estimating these constants from the spin-orbit coupling constants and fitting them to some experimental A-values. By this way the absolute phases of the experimental A((¹P)²D)- and A((¹P)²F)-values are obtained. Good agreement between calculated and most experimental data has been achieved.     

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.     

Current-induced coupling between conductance channels in membranes

The driven system of conducting channels in a nerve membrane is investigated. A current flow generates a coupling between the channels: the current through a channel is influenced by the presence of other conducting channels via the deformation of the equipotential surfaces within the media adjacent to the membrane. We derive an integral equation for the membrane voltageV(s) (s in the membrane plane) and solve it for different membrane conductance distributions(s) including models for stochastic distributions of conducting channels.V(s) is a nonlinear functional of(s). The system of coupled channels is compared with an Ising model. The system exhibits a multi-channel interaction which can be characterized by two different rangesd _int andD ₁. For a mean channel distanced ₀d _int interaction effects are negligible, and ford ₀D ₁ all channel-voltages are equal and thus represent a mean-field for the channels. Increasing conductivity of the medium decreasesd _int and increasesD ₁. With experimental data on sodium channels in nerve membranes we find:d _intd ₀, i.e. a 50% decrease of the channel-voltages by the interaction, andD ₁10³10⁴ d ₀, which indicates mean-field behaviour of the channels. In a subsequent paper we shall treat the statistics of channels which open and close stochastically under the influence of the local membrane voltage.     

Lifetime measurements in the Fe I spectrum using tunable dye laser excitation

Radiative lifetimes of single fine structure levels of the multiplets 3d⁶ 4s(a⁶ D)4p z⁵ D ⁰ and 3d⁷ (a⁴ F)4py ⁵F⁰ of the FeI spectrum were measured. The different levels were excited by a tunable dye laser which was pumped by a pulsed nitrogen laser. The exponential decay of the fluorescence was measured directly.     

Structure of Sufficient Quantum Coarse-Grainings

Let H and be finite-dimensional Hilbert spaces, T: B(H) B() be a coarse-graining and D ₁, D ₂ be density matrices on H . In this Letter the consequences of the existence of a coarse-graining : B() B(H) satisfying T(D _s )=D _s are given. (This means that T is sufficient for D ₁ and D ₂.) It is shown that D _s = _p=1 ^r _s (p) SH _s ^H (p)R^H(p) (s=1,2) should hold with pairwise orthogonal summands and with commuting factors and with some probability distributions _s (p) for 1 p r (s=1,2). This decomposition allows to deduce the exact condition for equality in the strong subadditivity of the von Neumann entropy.     

Multiconfiguration Hartree-Fock calculations in Cr5+, Mn6+ and Fe7+

The multiconfiguration Hartree-Fock (MCHF) method is used to calculate the excitation energies and oscillator strengths, of both the length (f _L) and velocity (f _V) forms, for 1s²2s²2p⁶3s²3p⁶3d² D→1s²2s²2p⁶3s²3p⁵3d^{2 2} P ⁰,² D ⁰,² F ⁰ transitions in Cr⁵⁺, Mn⁶⁺ and Fe⁷⁺ ions of the potassium isoelectronic sequence. Comparison is made with our earlier relevant results obtained by employing the configuration interaction (CI) method which is closely related to the MCHF method. Our present investigation demonstrates that the MCHF method is more accurate than the CI method in all ions of present consideration.     

STUDY OF HIGH-LYING EXCITED STATES OF RARE-EARTH ELEMENT Dy BY LASER RESONANCE IONIZATION SPECTROSCOPY

This paper describes the investigation of high-excited states of Dy. which includes the measurement of high Rydberg states and autoionizing states, by means of laser resonance ionization spectroscopy (LRIS). Two high Rydberg series (n>40), 4f¹⁰(⁵I₈) 6sns and 4f¹⁰(⁵I₈) 6snd, have been obtained by exciting the state of 4f¹⁰(⁵I₈) 6s6p (³P⁰₂) ⁵I⁰₈ using two-step laser excitation-electric field ionization method. With the data obtained, we determined the first ionization potential of Dy. It is 47901.7±0.6 cm^-1, that is. about one order more accurate than the results given in the literature. Using the same technique, we found 97 autoionizing states by exciting the state of 4f⁹5d6s(⁷H⁰₇).     

High resolution laser spectroscopy of Ba Rydberg atoms

The purpose of the present paper is to illustrate some selected aspects of high resolution laser spectroscopy of Rydberg atoms, rather than giving an extensive review of the state of the art. The following topics will be discussed: (i) Excitation and detection of Ba Rydberg atoms with principal quantum numbers up ton≲300; (ii) Stark effect and atomic diamagnetism of high-n Ba Rydberg states in thel-mixing region, (iii) Resonance in singlet-triplet mixing of 6snp¹P₁ and 6snd¹D₂ Ba Rydberg states deduced from hyperfine structure measurements.     

Flavor symmetry, K– mixing and new physics effects on CP violation in D and Ds decays

Flavor symmetry and symmetry breaking, K⁰– mixing and possible effects of new physics on CP violation in weak decay modes D^±→K_S,L+X^±, (K_S,L+π⁰)_K^*+X^± (for X=π,ρ,a₁) and D^±_s→K_S,L+X^±_s, (K_S,L+π⁰)_K^*+X^±_s (for X_s=K,K^*) are analyzed. Relations between D^± and D^±_s decay branching ratios are obtained from the ds subgroup of SU(3) and dominant symmetry-breaking mechanisms are investigated. A CP asymmetry of magnitude 3.3×10⁻³ is shown to result in the standard model from K⁰– mixing in the final-state. New physics affecting the doubly Cabibbo-suppressed channels might either cancel this asymmetry or enhance it up to the percent level. A comparison between the CP asymmetries in D^±_(s)→K_SX^±_(s) and D^±_(s)→K_LX^±_(s) can pin down effects of new physics.     

Lifetime measurements in the Fe I-spectrum using stepwise excitation by dye lasers

Using stepwise excitation by means of two nitrogen laser-pumped dye lasers the 3d ⁶ 4s(a ⁶ D) 4de ⁵ G ₆ level of Fe I at 50 523 cm^?1 was populated and its lifetime was determined from the decay of the subsequent fluorescence.