Doppelresonanzuntersuchungen zum Stark-Effekt des 4s 4p 3 P 1-Terms im Ca I-Spektrum

The influence of an electric field on the Zeeman-splitting of the 4s 4p ³P₁-level was investigated using the double resonance method. From the r.f.-resonance signals the tensor polarizability of the 4s 4p ³ P ₁-level was deduced to be α_ten(³ P ₁)=3.2(8) kHz/(kV/cm)². This value is used for an estimate of the oscillator strength of the infrared transition between the multiplets 4s 4p ³ P and 4s3d ³ D. Taking into account measured oscillator strengths of electric dipole transitions from the³ P ₁-level to other low lying levels one obtainsf(4s 4p ³ P→4s 3d ³ D)=0.09.     

Rumpfpolarisation des 4d 9 5s 22 D-Zustandes von Ag I

The hyperfine structure of the transition Ag I, 4d ⁹ 5s ²² D _3/2-4d ¹⁰5p ² P _1/2, λ=19,372 Å has been investigated by means of a photoelectrically recording Fabry-Pérot interferometer using separated isotopes. Evaluating the hfs-pattern by a digital analysis the following values for the magnetic dipole interaction constants have been obtained: $$A_{3/2}^{(109)} (d^9 5s^2 ) = - 12.11(6)mK; A_{1/2}^{(109)} (d^{10} 5p) = - 6.72(10)mK.$$ Using the knownA-factor of the other level of the configurationd ⁹ s ² and the values of the Ms anomalies of the levelsd ⁹ s ²² D _5/2 andd ¹⁰ s ² S _1/2 together with our result, the influence of the core polarization on theA-factors of the configurationd ⁹ s ² is discussed. Assuming that the used relativistic correction factors are correct, the influence of the core polarization cannot be due only to the unpaireds-electrons of the core, but must be described by the three-parameter hfs-Hamiltonian given by Harvey. Consequences for calculating the quadrupole moments from hfs data are mentioned.     

Polarisationseffekte in der Hyperfeinstruktur von65Cu I, 3d 94s 2 m 2 D

The hyperfinestructure of the transition⁶⁵CuI, 3d ¹⁰4p ² P _3/2—3d ⁹4s ² m ² D _5/2 was investigated by optical interferometric methods. For the hfs-factors the following values were found:A(⁶⁵Cu,m ² D _5/2)=26,79(3) mK andB(⁶⁵Cu,m ² D _5/2)=5,81(10) mK. The core polarization of them ² D-terms and the Sternheimer corrections in the calculation of the quadrupolmoment of copper 65 from theB-factors of the terms 3d ⁹ 4s² m ² D and 3d ¹⁰ 4p ² P _3/2. were discussed.     

Measurement of the lifetime of the3 P 2 and4 P 5/2 states in Ar16+ and Ar15+

Promptly decaying levels in Li- and Be-like Ar could be identified in the delayed x-ray and electron spectrum in addition to the four known metastable (1s2s)¹ S ₀, (1s2s)³ S ₁, (1s2p)³ P ₂, and (1s2s2p)⁴ P _5/2 states in He- and Li-like systems. The states having lifetimes of about 10^?14s still contribute to the spectrum observed 10^?9s after the ions have passed a foil. This observation is explained by cascading processes from states of high principal quantum numbern≧14. The measured lifetime of the⁴ P _5/2 state subtracting the contribution of cascades is (0.594±0.016) ns and slightly larger than the theoretically predicted value of 0.563 ns. The³ P ₂ state is depopulated at short distances behind the foil by cascading processes. Its measured lifetime of (1.44±0.08) ns compares to a theoretical value of 1.48 ns.     

Level-crossing-Untersuchung der Hyperfeinstruktur des 3d 10 4p 2 P 3/2-Terms von Cu63 und Cu65

The level-crossing technic has been used to investigate the hyperfinestructur of the 3d ¹⁰ 4p ² P _3/2-term in Copper I by scattering the resonance line λ=3248 Å on an atomic beam of separated isotop Cu⁶³ respectively Cu⁶⁵ in an external magnetic field. From the level-crossing signals values for the magnetic dipol interaction constantsA and for the electric quadrupol interaction constantsB are deduced to beeA(Cu⁶³)=(194,72±0,15) Mc/secB(Cu⁶³)=?(28,8±0,6) Mc/secA(Cu⁶⁵)=(208,57±0,15) Mc/secB(Cu⁶⁵)=?(25,9±0,6) Mc/sec. With theA-value of the 3d ¹⁰ 4p²P_1/2-term from optical measurements the ratioA(² P _3/2)∶A(² P _1/2)≈0,4 is about twice greater than for an unperturbetalkali-like²P-term. From the width of the level-crossing signals a mean lifetime of the 3d¹⁰ 4p²P_3/2-term τ=(7,0±0,2) · 10^?9 sec is deduced.     

Die Hyperfeinstruktur des übergangs Ag I, λ=19372 å

The hyperfinestructure of the transition AgI, 4d ⁹ 5s ^{2 2} D _3/2-4d ¹⁰ 5p ² P _1/2,λ=19372 å has been investigated with a photoelectric recording Fabry-Perot interferometer and digital data processing. The isotope shiftδ Ν _IS and the magnetic splittings factorsA have been determined to beδ Ν _IS=35,77 (12) mK,A(¹⁰⁹Ag, 5p ² P _1/2)=?7,00 (45) mK, andA(¹⁰⁹Ag, 4d ⁹ 5s ^{2 2} D _3/2)=?12,18 (23) mK. The influence of shielding effects on the value of the volume effect of the isotope shift and the influence of core polarisation on the splitting factors are discussed.     

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.     

Lifetime measurements of the3 P 2 and4 P 5 2/0 states in He- and Li-like titanium and chromium

Ti and Cr ions at specific energies of 3.6 MeV/N and 5.0 MeV/N have been excited by passing them through thinC foils. The emission ofK-x rays andK-Auger electrons have been investigated using a flat crystal spectrometer and an electrostatic cyclindrical mirror analyzer. The lifetimes of the (1s2p)³ P ₂ and (1s2s2p)⁴ P _5/2 states have been determined by applying the time-of-flight technique. The experimental resultsτ(Ti²⁰⁺,³ P ₂)=(404±40)ps,τ(Cr²²⁺,³ P ₂)=(215±35)ps,τ(Ti¹⁹⁺,⁴ P _5/2)=(236±12)ps, andτ(Cr²¹⁺,⁴ P _5/2)=(140±8)ps are compared with calculated lifetimes.     

Stark-Effekt-Untersuchungen der Hyperfeinstruktur der 5s25d2D3/2- und 5s25d2D3/2-Terme im In I-Spektrum

The level-crossing technique with combined electric and magnetic fields was used to investigate the hyperfine structure of the 5s ²5d ² D _3/2- and 5s ²6d ² D _3/2-stedes of the In I-spectrum. From the shifts of the level-crossing signals due to the Stark effect of the electric field the Stark constantsβ of both states were deduced: 5s ²5d ² D _3/2: ¦β¦=0.33(3) Mc/(kV/cm)² 5s ²6d ² D _3/2: ¦β¦=6(1) Mc/(kV/cm)². By theoretical calculations with wave functions of the Coulomb approximation one can show, that the Stark effect in both states is mainly due to admixtures of the 5s ²6p- resp.5s ²7p-configuration.     

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.     

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.     

Manifestation of the Coster-Kronig effect in the near-threshold electron-impact excitation of the Cd<Superscript>+</Superscript> ion

The near-threshold portions of the energy dependences of the effective excitation cross sections of the resonance transition 4d¹⁰5p²P_1/2° → 4d¹⁰5s²S_1/2 and the two-electron forbidden transition 4d⁹5s²²D_5/2 → 4d¹⁰5p²P_3/2° in the spectrum of the Cd⁺ ion were investigated by the spectroscopic method in crossed electron and ion beams. In the region of energy splitting of the ²P° and ²D levels, a significant resonance contribution of the autoionizing states of cadmium (decaying during the Coster-Kronig process) to the effective excitation cross sections of the noted transitions was revealed for the first time. It is found that the resonance contribution manifests itself much more strongly for the forbidden transition in comparison with the more intense resonance transition; i.e., the manifestation of the Coster-Kronig effect in the electron excitation of ions depends strongly on the cross section of the direct process. It is ascertained that, during the Coster-Kronig process, the main contribution to the resonance excitation of both the resonance and the two-electron forbidden spectral transitions is from the low-lying terms of the series of autoionizing states 4d¹⁰5p(²P_3/2°)ns, md and 4d⁹(²D_3/2)5s²ns, md, which are in the splitting region of the ²P_{1/2, 3/2}° and ²D_{5/2, 3/2} levels, rather than from the high-lying atomic autoionizing states of cadmium, which are located near the ionization limits (corresponding to the and ²P_3/2° and ²D_3/2 levels).     

Radiative decay and autoionization in the4 D-states of the 3d 94s5s configuration in CuI

The CuI 3d ⁹4s5s ⁴ D-states, which lie above the ionization limit, were populated by stepwise collisional and laser excitation. With respect to their total angular momentum, the⁴ D-states have completely different decay modes. Whereas the lifetimesτ(⁴ D _7/2)=8.2(4)·10^?9s andτ(⁴ D _1/2)=7.9(6)·10^?9 s are determinrd by radiative transitions and were measured by time-resolved spectroscopy, the lifetimesτ(⁴ D _5/2)=1.59(6)·10^?12s andτ(⁴ D _3/2)=1.28(5)·10^?12s are due to autoionization and were deduced from the widths of the excitation signals observed by ion detection.     

Lebensdauern und Oszillatorstärken im Sr I- und Ca I-Spektrum

Radiative lifetimes of some highly excited levels in Sr I were measured by zero-field level crossing technique. These levels have been populated using optical excitation starting from the metastable 4d 5s ¹ D ₂ or 5s5p ³ P _2,1,0 states. The high population of these metastable levels necessary for the experiments was obtained by a discharge in the pure Sr vapour burning in the atomic beam oven. The following lifetimes have been determined (in units of 10^?8 sec):τ(5s 6s³ S ₁)=1.09±0.11,τ(5s 5d ³D₁)=1.67±0.10,τ(5s4f¹ F ₃)=3.43±0.28,τ(4d5p ¹ D ₂)=2.19±0.16,τ(5p ^{2 3}P₁)=0.88±0.12,τ(5p ^{2 3} P ₂)=0.78 _?0.10 ^+0.26 . These results are compared with lifetimes derived from oscillator strengths given in the literature, and the reliability of different oscillator strengths tables is discussed. A corresponding discussion is given for radiative lifetimes of some levels in Ca I published previously. Good agreement with data derived from arc emission oscillator strengths has been found. Ca lifetimes are fairly well consistent with oscillator strengths calculated with semiempirical scaled Thomas-Fermi-wave functions.     

Isotope shift and hyperfine structure of the transition5d6s 2 2 D 3/2-5d6s6p 4 F 3/2 of Lu175 and Lu176

Using a tunable single mode dye laser the isotope shift of the 573.7 nm-line between the isotopes Lu¹⁷⁵ and Lu¹⁷⁶ has been determined to be IS(176?175, 573.7 nm)=?394(5) MHz yielding a change of mean square nuclear radii ofδ〈r ²〉=0.022(5) fm². In addition from our measurements the following values of the hyperfine splitting constantsA andB could be deduced Lu¹⁷⁶ 5d6s6p ⁴ F _3/2:A=?651.4(0.3) MHz,B=2,494(4) MHz 5d6s ^{2 2} D _3/2:A=138.0(0.3) MHz,B=2,131(3) MHz Lu¹⁷⁵ 5d6s6p ⁴ F _3/2:A=?924.7(0.5) MHz,B=1,767(4) MHz.     

Level-crossing-Untersuchung der Hyperfeinstruktur des angeregten 32 P 3/2- und 42 P 3/2-Zustands von Na23

The hyperfine structure of the excited 3² P _3/2- and 4² P _3/2-state of Na²³ has been investigated in a level-crossing-experiment by means of a detailed analysis of the dependence of the scattered resonance light as a function of the magnetic field. From the experimental curves the following results for the hyperfine structure constantsA andB and for the lifetimesΤ were deduced 3² P _3/2-state: 4² P _3/2-state:A=18.65(10)Mc/sA=6.006(30)g _j/1.334Mc/sB=2.82(30)Mc/sB=0.86 (9)g _j/1.334Mc/sΤ=1.60 (3) · 10^?8sΤ=6.56 (25)1.334/g_j·10^?8 s. The nuclear electric quadrupolemoment of Na²³ derived from these values isQ=0,097 · 10^?24 cm², where the Sternheimer-correction has been applied.     

Oxidation of a cesium-covered Ni (1 1 0) surface studied by metastable-induced electron spectroscopy

An initial stage of oxidation of a cesium-covered Ni (1 1 0) surface has been studied by metastable-induced electron spectroscopy (MIES) and low-energy electron diffraction (LEED). The MIES brought spectra with Cs 6s induced peak (P_6s), Cs 5p (P_5p), O 2p induced peak (P_ox) and a structure related to the substrate Ni 3d states (P_3d). The work function change Δφ showed an oscillatory behavior in the progress of surface oxidation. The process is divided into three stages: (i) at low O₂ exposures, Δφ > 0 with unchanging P_5p and P_6s; (ii) at moderate exposures, Δφ < 0 with a drastic decrease in the P_6s intensity; (iii) at higher exposures, Δφ > 0 with shifts of peaks P_5p and P_ox to higher energies, together with an appearance of peak P_3d. A three-step model of initial oxidation of alkali-covered Ni (1 1 0) surfaces is presented.     

Hyperfine-structure and isotope-shift measurements in the 6s 5d↔6p 5d transitions of Ba I in the far-red spectral region

Measurements of the hyperfine structures in the 6p5d ¹ D ₂,³ D ₁ and³ F _{2, 3, 4} states of¹³⁵Ba and¹³⁷Ba, and isotope-shifts in several far-red transitions between the 6s 5d and 6p 5d configurations, as well as the transition 6s ^{2 1} S ₀→6s6p ³ P ₁ at 7,911 Å have been performed using high-resolution laser spectroscopy on a collimated atomic beam of natural barium. An analysis of the magnetic-dipole interaction in the 6p 5d configuration using effective one- and two-body hyperfine operators is presented. In particular the contact interaction was studied with respect to the correlation between the two valence electrons. Effects of strong configuration interaction were found. From a King-plot analysis of the isotope shift term- andJ-dependence of the field shift have been evaluated for the transitions between the 6s 5d and 6p 5d configurations. Relativistic Hartree-Fock (RHF) calculations have been performed of electron densities at the nucleus for six different configurations in Ba I and Ba II. The RHF calculations reproduce the experimental King-plot slopes quite well, while the absolute values, of the changes in electron density at the nucleus for the studied transitions, are found to be 9% lower than the results derived from a muonic experiment.     

Termanalyse der 4d 9 5s 5d-Konfiguration im Bogenspektrum des Silbers

The arc spectrum of silver has been remeasured in the range of 1100 to 9800 Å. This yielded some 140 new lines. Analysing these lines together with about 50 previously unidentified lines of Shenstone established 20 new levels. The configurations 4d ⁹ 5s 5p and 4d ⁹ 5s 6s are now completely analysed. In the 4d ⁹ 5s 5d-configuration about half of the expected levels were identified. Two new 4d ⁹ 5s 7s levels were found.     

Microstructures, surface bonding states and room temperature ferromagnetisms of Zn0.95Co0.05O thin films doped with copper

Zn_0.95−xCo_0.05Cu_xO (ZCCO, where x = 0, 0.005, 0.01 and 0.015) thin films were deposited on Si (1 0 0) substrates by pulsed laser deposition technique. Crystal structures, surface morphologies, chemical compositions, bonding states and chemical valences of the corresponding elements for ZCCO films were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and X-ray photoelectron spectroscopy (XPS). XRD and FESEM results indicate that crystallite sizes of the highly (0 0 2)-oriented ZCCO films slightly decrease with increasing Cu content. When the Cu content increases from 0 to 0.015, Zn 2p_3/2, Co 2p, Cu 2p_3/2 and O 1s peaks of the ZCCO film shift towards higher or lower binding energy regions, and the reasons for these chemical shifts are investigated by fitting the corresponding XPS narrow-scan spectra. Both in-plane and out-of-plane magnetization-magnetic field hysteresis loops of the ZCCO films reveal that all the films have room temperature ferromagnetisms (RTFMs). The conceivable origin of the RTFM is ascribed to the combined effects of the local structural disorder resulted from (Co²⁺, Cu²⁺, Cu¹⁺)-cations which substitute Zn²⁺ ions in the ZnO matrices, ferromagnetic coupling between coupled dopant atoms caused by Co²⁺ (3d⁷4s⁰) and Cu²⁺ (3d⁹4s⁰) spin states, and exchange interactions between the unpaired electron spins originating from lattice defects induced by Cu doping in the Zn_0.95Co_0.05O matrices.