Regular Article – Atomic Physics
Isotope shift measurements in 94 spectral lines of singly-ionized dysprosium atom (Dy+) in 330–385 nm region and comments on the electronic configuration assignments to the odd and even-parity energy levels of Dy II
Department of Physics, Aligarh Muslim University, 202002, Aligarh, India
2 Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, 400085, Trombay, Mumbai, India
Accepted: 17 October 2022
Published online: 21 November 2022
Isotope shift (IS) Δν(160Dy − 164Dy) measurements in 94 spectral lines of singly-ionized dysprosium atom (Dy II) in 330–385 nm were carried out on a Recording Fabry–Perot Spectrometer using highly enriched 160Dy and 164Dy isotopes. IS data for 72 spectral lines of Dy II are being reported for the first time. The level isotope shift ΔT(160Dy − 164Dy) has been evaluated for 74 odd-parity energy levels. Experimentally evaluated level isotope shift ΔT of the energy levels are sensitive probe to check the theoretical composition of the mixed configurations assigned to the energy levels. The verification of the theoretical composition of 29 odd-parity levels assigned earlier to [4f9(5d + 6s)2 + 4f106p] configurations has been carried out and good agreement has been observed between the theoretically expected and the experimentally evaluated level isotope shifts ΔT values within the available accuracy of our measurements. The known odd-parity energy levels of Dy II between 32,000 and 46,000 cm−1 have no configuration assignments and presently it is not easy to carry out theoretical calculation of the energy levels in this region. The present study has enabled us to evaluate ΔT values of 35 unassigned high lying odd-parity energy levels lying in between 33,000 and 39,600 cm−1. These ΔT values have been used to suggest the possible dominant electronic configurations to these unassigned high lying odd- parity energy levels: 8 levels to 4f106p configuration, 1 level to 4f95d2, 13 levels to (4f106p + 4f95d2) and 13 levels to (4f106p + 4f95d2 + 4f95d6s). The observed isotope shifts in 13 spectral lines involving transitions from the high even-parity levels of 4f95d6p and 4f96s6p to the low odd-parity energy levels of 4f95d6s has enabled the confirmation of the assignments of 10 energy levels to 4f95d6s, 10 levels to 4f95d6p and 3 levels to 4f96s6p configuration.
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