Fine and hyperfine structure for 4f 115d6s6p in Er I

Abstract

Hyperfine structure (hfs) constants in neutral erbium of 22 levels of the configuration 4f115d6s6p with four open electron shells have been determined for the only stable odd isotope 167Er, using Doppler reduced saturation spectroscopy in form of intermodulated optogalvanic and saturated absorption spectroscopy. From the experimental data for altogether 29 levels we evaluated the hfs-parameters in the effective tensor operator formalism. For this purpose we performed a fine structure analysis of the sub-configuration 4f11(4I)5d6s6p in LS-coupling, confirming and extending the preliminary classification of even parity Er I levels. The relativistic magnetic and electric one-electron parameters were fitted to the experimental data by a least squares fit procedure: a4f01 = –156.6 (1.7) MHz, a5d01 = –30 (10) MHz, a6p01 = –114 (24) MHz, a6s10 = –1630 (35) MHz, b4f02 = –7960 (200) MHz, b5d02 = 3460 (180) MHz, b6p02 = 5440 (270) MHz, gave the best results in the case where all parameters of one electron shell were held in a fixed ratio. The corresponding ⟨r–3⟩ nlkskl values are compared with those known for other lanthanide elements, extending the present systematic hyperfine studies. Finally, effective nuclear quadrupole moments have been determined and will be discussed.