Semi-empirical calculations of radiative decay rates in Mo II. A comparison between oscillator strength parametrization and core-polarization-corrected relativistic Hartree-Fock approaches

Abstract

We present a semi-empirical determination of Mo II radiative parameters in a wide wavelength range 1716-8789 Å . Our fitting procedure to experimental oscillator strengths available in the literature permits us to provide reliable values for a large number of Mo II lines, predicting previously unmeasured oscillator strengths of lines involving 4d 4 5p and 4d 3 5s5p odd-parity configurations. The extracted transition radial integral values are compared with ab-initio calculations: on average they are 0.88 times the values obtained with the basic pseudo-relativistic Hartree Fock method and they agree well when core polarization effects are included. When making a survey of our present and previous studies and including also those given in the literature we observe as general trends a decreasing of transition radial integral values with filling nd shells of the same principal quantum numbers for n d k ( n + 1)s → n d k ( n + 1)p transitions.

Second spectrum of Chromium (Cr II), Part II: Radiative lifetimes and oscillator strengths of transitions depopulating low lying 3d44p levels

“…In this table we have inserted also the transition radial integral value of 3d 4 4p-3d 4 4d, admittedly with less good accuracy since we have rooted out only the 3d 4 4d contributions to 3d 4 4s levels. Let us point out that the obtained ⟨3d 4 4s|r 1 |3d 4 4p⟩ = 2.932(0.003) is very close to the predicted value reported in our previous work [9], i.e. 3.00 (0.02).…”

“…In the present work one of our aims is to extend the study of transition radial integral behavior to another ion, located in the same row of the periodic Table, namely Cr II, and by the way to check our predicted transition radial integral value given in [9]. To extract this latter value we can take advantage of experimental oscillator strengths or transition probabilities, plentifully available in literature [10][11][12][13][14].…”

Second spectrum of chromium (Cr II), Part III: Radiative lifetimes and transition probabilities from highly excited 3d45s levels

“…2.139, scaled by a factor 0.92. This confirms the trends we already highlighted in [15] for several singly ionized ions.…”

“…The reader is invited to read one of our previous papers, for instance [2,14,15], in which the formulas and the approaches we have used to achieve our calculations are presented in detail. Usually before performing OSP calculations, we first have to select the strongest lines, not blended, and preferably those corresponding to transitions between levels with a limited number of leading components.…”

Ab initio and semi‐empirical atomic structure calculations: Applications to the 5p‐6s transitions for the Mo II ion

“…Semi‐empirical radiative parameters for Mo II have been calculated in the wavelength range from 1716 to 8789 Å by Bouazza et al (2017).…”