Magnetic hyperfine structure in the 4p 3 and 4p 25s configurations of arsenic

The magnetic hyperfine structure factorA of the quasi-totality of the levels of the low 4p ³ and 4p ²5s configurations of As I has been measured by Fabry-Perot interferometry in the far UV range. A good agreement is observed between experimental results and theoretical evaluations, which allows us to confirm that the 4p ²5^s configuration only mixes very weakly (less than 1%) with 4s4p ⁴.     

The 4p 3 (2 P)ns,nd configurations of Se I

The photoabsorption spectrum of Se I has been photographed in the 1100–900 Å wavelength region, using a flash-pyrolisys system: about twenty lines were observed, most of them for the first time. With the support of Hartree-Fock calculations they have been identified and assigned to the 4p ⁴ → 4p ³ ns ³ P(n=7–14) and 4p ⁴ → 4p ³ nd ³ D(n=5–17) series, both converging on the limit 4p ³(² P _3/2).     

Stark-mixing effect on the 6p 2 1 S 0−6p 2 3 P 2 transition in Pb I

The intensity of the 531.5 nm electric-field-quench radiation has been measured on a thermal beam of neutral Pb atoms in the metastable 6p ^{2 1} S ₀ state. The measurement yields a Stark-mixing amplitude for transition between the 6p ^{2 1} S ₀ and 6p ^{2 3} P ₂ states. Combining this result with available experimental data sets an upper limit for the 6p 7s ³ P ₁ → 6p ^{2 1} S ₀ transition probability:A _ki <1.79·10³ s ^?1. Calculations for the 6p 7s → 6p ² and 6p 8s → 6p ², as well as transition rates of forbidden lines inside 6p ² configuration of PbI are presented and compared with existing experimental data.     

Analysis of the 5p6p configuration of Xe V

The spectrum of four times ionized Xenon (XeV), has been observed in the 500–6800 Å range and 84 new lines have been identified as transitions between levels of 5s5p ³, 5s ²5p5d, 5s ²5p6s, 5s ²5p ², and 5s ²5p6p configurations. Nine new levels belonging to the configuration 5p6p have been determined. The results of this analysis are supported by Hartree-Fock calculations. The configurations are interpreted by fitting the theoretical energy parameters to the observed levels using least-squares techniques.     

The 4s 24p 3-4s4p 4 transition in AsI-like AgXV

Some terms of the 4s4p ⁴ configuration in RuXII, RhXIII and PdXIV ions can be improved and all the energy values of the configuration in AgXV can be predicted theoretically by means of a configuration-interaction ab initio analysis for the level structure of the 4s4p ⁴ configuration along the AsI sequence of KrIV-AgXV ions. Calculations of the wavelengths and oscillator strenghts are presented for the 4s ²4p ³-4s4p ⁴ transition in AgXV.     

Investigations of radiative lifetimes in the 3p5p configuration of neutral silicon

Lifetimes for the³ S ₁,³ P _{0, 1, 2} and³ D _{1, 2, 3} states in the 3s ²3p5p configuration of silicon have been determined using stepwise dye laser excitation and time resolved detection. A comparison is made with theoretical values, calculated using multi-configuration Hartree-Fock wavefunctions. Laser-evaporation was used to produce free silicon atoms by focusing a Nd: YAG laser on a rotating silicon target.     

Beam-foil lifetime data for 3s 3p 3 and 3s 2 3p 3d levels of Si-like Ni14+

In the EUV spectrum of foil-excited 24 MeV Ni ions the decays of the 3s 3p ³ and 3s ² 3p 3d levels to the 3s ² 3p ² levels of the ground configuration have been observed. For most of the levels decay curves have been obtained. The lifetime results compare well with predictions from semi-empirically scaled HXR calculations. Some problems with cascade repopulations will be discussed.     

Hyperfine structure studies in the mixed configurations (4p 2 4d+4s 4p 4) of arsenic

The magnetic hyperfine structures of some levels of the 4p ² 4d configuration which mixes strongly with the 4s 4p ⁴ configuration, have been measured for the first time, using the Fabry-Perot technique in the far UV range. A good agreement is observed between experimental results and theoretical evaluations.     

Multiple photoionization from 3p excitation of Kr and 4p excitation of Xe

The photoionization cross sections for multiply charged ions produced by 3p excitation of Kr and 4p excitation of Xe have been obtained by means of a time-of-flight mass spectrometer and synchrotron radiation. It is found that the main formation of doubly to quadruply charged ions in both Kr and Xe is caused from the each initialp-hole state through a Coster-Kronig transition followed by Auger or double Auger processes. The formation of singly charged ions in these excitation energy regions is caused by direct photoionization from outermost shell electrons in both Kr and Xe. Triply charged ions are prominently produced among the multiply charged ions. The quadruple photoionization cross sections show clearly the structures due to the Rydberg series, 3p ^?1 nl of Kr and 4p ^?1 nl of Xe. Their main structures were assigned to the 3p ^?1 nd series in Kr and the 4p ^?1 nd series in Xe.     

Behaviour of the 3p 511s’ [1/2]1 level of Argon I in a strong magnetic field

The properties of the autoionizing 3p ⁵11s’ [1/2]₁ Argon I level have been experimentally studied in the presence of a strong magnetic field (2.14-2.22 T). Quasi- Landau type oscillations have been observed in the width and position of the 3p ⁵-4p[1/2]₀ -3p ⁵11s’ [1/2]₁ exciting transition. The results provide an additional support for earlier observations of Lemoigne et al. [7]. No evidence for similar oscillations in magnetic field dependence of the Fano q parameter was observed.     

Lifetime of 2s2p 23s 3 P in N II and other allowed triplet transitions

Systematic transition calculations have been performed for all triplet decay channels from 2s2p ²3s ³ P of N II. The lifetime of 0.505 ns compares favourably with experiment. Transitions in absorption from the 2s ²2p ^{2 3} P ground state have also been determined along with a number of other triplet transitions. Length and velocity forms of thef-value are in agreement at the 2–3% level for most transitions.     

Electric quadrupole transition rates for even parity levels of Si I

Non-relativistic Hartree-Fock radial wavefunctions have been used to provide ab initio estimates of E2 transition rates from levels of the 3p ² configuration to those of the 3p4f configuration in Si I. Where it is possible to make comparison with experimental data the results are in reasonable qualitative accord with recent multiphoton ionization observations.     

Wavelength and isotopic shift measurements of the3S(3s 4s) −3P(3s 3p) MgI transitions

The wavelengths of the³S(3s 4s) ?³P(3s 3p) MgI transitions have been measured for the²⁴Mg isotope with a precision of ±2 × 10^?7; moreover the isotope shifts of the above transitions have been measured for the three natural Mg isotopes as well as the hyperfine constants of the³S(3s 4s) level of²⁵Mg. The measurements have been performed in a metastable atomic beam.     

Collisional depolarization of excited114Cd 5s5p 3 P 1 atoms by collisions with molecular gases

Depolarization of excited¹¹⁴Cd 5s5p ³ P ₁ atoms induced by collisions with various molecular gases (N₂, H₂, D₂, CO, CO₂, CH₄, C₂H₆, C₂H₄) has been investigated using polarized fluorescence spectroscopy. After pulsed optical excitation of the Cd 5³ P ₁ level with appropriately polarized light the temporal behaviour of Zeeman quantum beats has been observed showing the influence of collisional destruction of orientation and alignment. By analyzing the signal curves at different molecular gas pressures the corresponding depolarization cross sections for¹¹⁴Cd atoms in the 5³ P ₁ state have been obtained. With regard to a test of a nuclear spin decoupling model for the collisions the cross sections were compared with previously measured hyperfine structure transfer cross sections of¹¹³Cd 5s5p ³ P ₁ atoms.     

Theoretical and experimental analysis of the fine structure and hyperfine structure in the configurations 5p6s and 5p6p of the antimony II spectrum

From 17 transitions in the singly ionized Sb II spectrum the hyperfine structure (A andB splitting constants) of the complete excited configurations 5p6s and 5p6p were determined by means of optical interference spectroscopy. In addition, a theoretical analysis both of the fine structure and also of the hyperfine structure was carried out (in the case of 5p6p of the general typenpn′p for the first time in literature). For the 3 levels 5p6p ³ P ₁, 5p7p ³ D ₂ and 5p6p ¹ P ₁ a different classification was found and consistent values for the fine structure parameters, mixing coefficients and single electron hyperfine structure splitting parametersa _nl ^ik andb _nl ^ik were obtained. The three new determinations in Sb II of the quadrupole moment (in barn) of¹²¹Sb (Q(5p6s)=?0.55(5);Q(5p6p)=?0.57(5) from the 5p-electron andQ(5p6p)=?0.7(2) from the 6p-electron) are well agreeing with each other but differ to former values from SbI. The core polarization and isotope shift of the lines, however, are compatible with our former results in SbI.     

HFS constants of Be I 1s22s2p 3p0, B I 1s22s2p24P and B I 1s22s2p22D obtained from the non-closed shell many-electron theory for excited states

Using the non-closed shell many-electron theory for excited states of Sinano?lu we compute the hyperfine structure constants of Be I 1s²2s2p ³P⁰, B I 1s²2s2p²⁴P and B I 1s²2s2p²²D. The quadrupole moment of ⁹Be is also newly determined to be, Q = 0.05494 barns.     

Calculation of the photo-electrons angular distribution asymmetry parameter β2p near the (3s3p)1 P resonance of He*

Near the (3s3p)¹ P resonance of He, we have calculated the photoelectrons angular distribution asymmetry parameter β_2p in the diagonalization approximation. Using the measured value of β _n=2 near the (3s3p)¹ P level obtained by Lindle et al. in the resonance photo-ionization of He to He^?(n=2), we have estimated the ratioR=σ_2p /σ_2s of the partial 2p photo-ionization cross section to the partial 2s photo-ionization cross section. Our calculation supports the result that in the resonance region, the formation of ions in the 2p level dominates over the 2s level. This is in good agreement with the experimental and most of the theoretical results reported to date.     

Beam-foil measurements of the 3p3P and 3p3D energy levels in O III

The beam-foil excitation technique has been applied to study the spectra of oxygen in the 200–500 nm wavelength region. Decays of the 3p³P and 3p³D energy levels in O III have been identified unambiguously and the ANDC (arbitrarily normalized decay curve) technique was utilized to investigate the influence of cascades on the lifetimes of these levels. These lifetimes are compared with theoretical calculations and data from other workers.     

Calculation of 2p 4(3 P)nl(l=s,d) Rydberg spectra of the fluorine isoelectronic sequence

The basic structure parameters of 2p ⁴(³ P)ns and 2p ⁴(³ P)nd (J=1/2, 3/2 and 5/2) Rydberg spectra for the fluorine isoelectronic sequence from FI to NiXX, as functions of effective nuclear charge, are calculated by using the eigenchannel quantum-defect theory. The results can be interpreted in terms of the variations of electrostatic and spin-orbit interactions along the sequence. A vast amount of basic atomic data can be obtained with these parameters as input. Some numerical examples are given, in which our results are in perfect agreement with experimental.     

Lifetime measurements of the 3d 94s(1 D) 4p configuration of Cu I

The radiative lifetimes of the levels in the 3d ⁹4s(¹ D)4p configuration of Cu I are measured. The levels are excited from the metastable 3d ⁹4s ^{2 2} D _3/2,5/2 levels. The metastable Cu atoms are generated in a pulsed hollow cathode discharge. The levels investigated are populated with a 35-ps laser pulse at wavelengths around 220 nm. The laser induced fluorescence signal is detected. The lifetime of the 3d ⁹4s(³ D)4p ⁴ D _1/2 level is also determined by direct excitation from the ground state. A comparison with calculated literature values is given.