High Lying Precise Resonance Energies from Photoionization Studies of Se3+ and Rb+ Ions Using the Screening Constant per Unit Nuclear Charge Formalism (original) (raw)
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Calculations of high-lying energy resonances of 12 Rydberg series due to the 4p → nd and 4p → ns transitions from the 4s24p3 3S°3/2 ground-state and the 4s24p3 2P°3/2,1/2 and 4s24p3 2D°5/2,3/2 metastable states of the Se+ ion are reported. The calculations believed to be the first theoretical ones are performed using the Screening Constant per Unit Nuclear Charge (SCUNC) method up to n = 40. Analysis of the present results is achieved in the framework of the standard quantum-defect theory and of the SCUNC-procedure by calculating the effective nuclear charge. For many resonances, the SCUNC-method reproduces the ALS measurements excellently [Esteves et al., Phys. Rev. A, 84 013406 (2011)] up to n = 25. However, for some resonances belonging to the 4s24p2 (1D2)nd (2D) and 4s24p2 (1D2)ns (2D) and to the 4s24p2 (1D2)nd (2S) and 4s24p2 (1D2)nd (2P1/2) Rydberg series, the ALS data overlap at high n values. In addition, negative quantum-defect values were determined where positive values a...
Single photoionization of the Kr-like Rb II ion in the photon energy range 22-46.0 eV
MNRAS, 2019
Single photoionization cross-sections for Kr-like Rb + ions are reported in the energy (wavelength) range from 22 (564 Å) to 46 eV (270 Å). Theoretical cross-section calculations for this trans-Fe element are compared with measurements from the ASTRID radiation facility in Aarhus, Denmark and from the dual laser plasma technique, at respectively 40 and 35 meV FWHM energy resolution. In the photon energy region 22-32 eV the spectrum is dominated by excitation auto-ionizing resonance states. Above 32 eV the cross-section exhibits classic Fano window resonances features, which are analysed and discussed. Large-scale theoretical photoionization cross-section calculations, performed using a Dirac Coulomb R-matrix approximation are benchmarked against these high-resolution experimental results. Comparison of the theoretical work with the experimental studies allowed the identification of resonance features and their parameters in the spectra in addition to contributions from excited metastable states of the Rb + ions.
Screening-constant-by-unit-nuclear-charge calculations of high lying and states of the ion
Atomic Data and Nuclear Data Tables, 2013
We report in this paper energy positions of the (2pns) 1,3 P • and (2pnd) 1,3 P • Rydberg states (n = 3-60) and resonance widths of the (2pns) 1 P • and (2pnd) 1 P • (n = 20) members of these series of the B + ion. Calculations are performed in the framework of the screening-constant-by-unit-nuclear-charge method. Along all the series investigated, the quantum defect is almost constant up to n = 60. The present results compare very well to available theoretical and experimental literature values up to n = 20. The data presented in this work may be a useful guideline for investigators considering the photoionization spectrum of the B + ion.
Radiation Physics and Chemistry, 2019
Accurate high lying resonance energies of the (3d 9 4s 3 D 3,2,1)np and the (3d 9 4s 1 D 2)np (n = 5-40) Rydberg series originating from the (3d 10 4s 1 S 1/) ground state of the Cu-like Zn + ion are reported. Calculations are performed in the framework of the Screening Constant by Unit Nuclear Charge (SCUNC) formalism. The results obtained compared very well with high resolution ALS measurements along with DARC, Dirac Atomic R-matrix Codes computations [Hinojoha et al., MNRAS, 470, 4048 (2017)]. Analysis of the present results is achieved in the framework of the standard quantum-defect theory and of the SCUNC-procedure based on the calculation of the effective charge. It is demonstrated that the SCUNC-method can be used to assist fruitfully experiments for identifying narrow resonance energies due to overlapping peaks New high lying accurate resonance energies (n = 16-40) are tabulated as benchmarked data for interpreting spectra from this trans-Fe element in astrophysical objects.
Atomic Data and Nuclear Data Tables, 2014
Energy positions and quantum defects of the 4s 2 4p 4 (1 D 2 , 1 S 0) ns, nd Rydberg series originating from the 4s 2 4p 5 2 P • 3/2 ground state and from the 4s 2 4p 5 2 P • 1/2 metastable state of Kr + are reported. Calculations are performed using the Screening Constant by Unit Nuclear Charge (SCUNC) method. The results obtained are in suitable agreement with recent experimental data from the combined ASTRID merged-beam set up and Fourier Transform Ion Cyclotron Resonance device (Bizau et al., 2011), ALS measurements (Hinojosa et al., 2012), and multi-channel R-matrix eigenphase derivative calculations (McLaughlin and Balance, 2012). In addition, analysis of the 4s 2 4p 4 (1 D 2)nd and the 4s 2 4p 4 (1 S 0)nd resonances is given via the SCUNC procedure. The excellent results obtained from our work point out that the SCUNC formalism may be used to confirm the results of the analysis from the standard quantum-defect expansion formulas. Eventual errors occurring in the analysis can then be automatically detected and corrected via the SCUNC procedure.
Physical Review A, 2003
We have measured the photoabsorption spectra of the Kr-like ions Rb ϩ and Sr 2ϩ at photon energies corresponding to the excitation of 4s-np resonances using, the dual laser plasma photoabsorption technique. Dramatic changes in the line profiles, with increasing ionization and also proceeding along the Rydberg series of each ion, are observed and explained by the trends in 4s-transition amplitudes computed within a framework of configuration-interaction Pauli-Fock calculations. Total photoionization cross sections show very good agreement with relative absorption data extracted from the measured spectra.
Physical Review A, 2017
The XCHEM approach interfaces well established quantum chemistry packages with scattering numerical methods in order to describe single ionization processes in atoms and molecules. This should allow one to describe electron correlation in the continuum at the same level of accuracy as quantum chemistry methods do for bound states. Here we have applied this method to study multichannel photoionization of Ne in the vicinity of the autoionizing states lying between the 2s 2 2p 5 and 2s2p 6 ionization thresholds. The calculated total photoionization cross sections are in very good agreement with the absolute measurement of Samson et al [J. Elect. Spect. Rel. Phen. 123, 265 (2002)], and with independent benchmark calculations performed at the same level of theory. From these cross sections, we have extracted resonance positions, total autoionization widths, Fano profile parameters and correlation parameters for the lowest three autoionizing states. The values of these parameters are in good agreement with those reported in earlier theoretical and experimental work. We have also evaluated β asymmetry parameter and partial photoionization cross sections and, from the latter, partial autoionization widths and Starace parameters for the same resonances, not yet available in the literature. Resonant features in the calculated β parameter are in good agreement with the experimental observations. We have found that the three lowest resonances preferentially decay into the 2p −1 d continuum rather than into the 2p −1 s one [Phys. Rev. A 89, 1 (2014)], in agreement with previous expectations, and that in the vicinity of the resonances the partial 2p −1 s cross section can be larger than the 2p −1 d one, in contrast with the accepted idea that the latter should amply dominate in the whole energy range. These results show the potential of the XCHEM approach to describe highly correlated process in the ionization continuum of many electron systems, in particular molecules, for which the XCHEM code has been specifically designed.
Energy and radiative properties of the (3)Π1 and (5)Σ+1 states of RbCs: Experiment and theory
Physical Review A, 2017
We combined high resolution Fourier-transform spectroscopy and large scale electronic structure calculation to study energy and radiative properties of the high-lying (3) 1 Π and (5) 1 Σ + states of the RbCs molecule. The laser induced (5) 1 Σ + ,(4) 1 Σ + ,(3) 1 Π →A(2) 1 Σ + ∼ b(1) 3 Π fluorescence (LIF) spectra were recorded by the Bruker IFS-125(HR) spectrometer in the frequency range ν ∈ [5500, 10000] cm −1 with the instrumental resolution of 0.03 cm −1. The rotational assignment of the observed LIF progressions, which exhibit irregular vibrational-rotational spacing due to strong spin-orbit interaction between A 1 Σ + and b 3 Π states was based on the coincidences between observed and calculated energy differences. The required rovibronic term values of the strongly perturbed A∼b complex have been calculated by coupled-channel approach for both 85 Rb 133 Cs and 87 Rb 133 Cs isotopolgues with accuracy of about 0.01 cm −1 , as demonstrated in [A. Kruzins et. al., J. Chem. Phys. 141,184309 (2014)]. The experimental energies of the upper (3) 1 Π and (5) 1 Σ + states were involved in a direct-potential-fit analysis performed in the framework of inverted perturbation approach. Quasi-relativistic ab initio calculations of the spin-allowed (3) 1 Π,(5) 1 Σ + → (1-4) 1 Σ + ,(1-3) 1 Π transition dipole moments were performed. Radiative lifetimes and vibronic branching ratios of radiative transitions from (3) 1 Π and (5) 1 Σ + states were evaluated. To elucidate the origin of the Λ-doubling effect in the (3) 1 Π state the angular coupling (3) 1 Π-(1-5) 1 Σ + electronic matrix elements were calculated and applied for the relevant q−factors estimate. The intensity distributions simulated for the particular (5) 1 Σ + ;(3) 1 Π →A∼b LIF progressions have been found to be remarkably close to their experimental counterparts.