Isotope shift measurements in 555-833 nm wavelength region with FTS and electronic configuration assignments to the energy levels of neutral dysprosium atom

Abstract

Precise spectroscopic measurements of isotope shift (IS), Δσ (160Dy - 164Dy) have been carried out in the 258 atomic emission lines of neutral dysprosium covering 555–833 nm wavelength region, of which IS data for 198 lines is being reported for the first time. The present measurements have contributed significantly to understanding the complex Dy I atomic structure, which enabled us to report the level isotope shift, ΔT (160Dy - 164Dy) for 100 even- parity and 82 odd- parity energy levels out of which ΔT (160Dy - 164Dy) values for 45 even- and 36 odd- parity levels are new. Earlier tentative assignments of 15 even levels to 4f95d6s6p and 5 even- levels to 4f106s6d configuration have been confirmed in the present study. New configuration assignments have been made to 10 even levels and also 5 each assigned to 4f95d6s6p and 4f106s6d configurations. The validity of 10 odd-parity energy levels theoretically assigned earlier to the mixed (4f95d6s2+4f106s6p+4f95d26s) configurations has been verified using newly derived experimental level isotope shifts, ΔT (160Dy-164Dy) values. Tentative assignments of 4f105d6p configuration confirmed for the 5 odd levels lying between 35029.50 cm−1 (J=8) - 37836.50 cm−1 (J=9). The present investigations have led to the first identification of two almost pure levels of 4f105d6p configuration at 35777.79 cm−1 (J=8) and 36260.17 cm−1 (J=9). The ΔT (160Dy- 164Dy) values for 2 levels of 4f106s7p configuration have been evaluated by us for the first time, whose configuration assignments have been confirmed presently.