Abstract

Eight low-lying levels of Er ii 4f¹² 6s have been observed to be grouped according to their energy in four close pairs. The centers of gravity of the pairs correspond to the energies of the four lowest levels of the core 4f¹²; the spacings between the two components of the pairs depend on the Coulomb interaction between the s electron and core and are determined by the single Slater integral G³(4f,6s). The levels of the core can be fitted very closely with integrals F_k(4f,4f) whose ratios one to another are the same as those for a hydrogenic 4f eigenfunction. The integral F₂(4f,4f) is found to be 427 cm⁻¹ and ζ_f the spin-orbit coupling constant, 2237 cm⁻¹. The spacings are fitted moderately well by a value of 1580 cm⁻¹ for G³; discrepancies are ascribed to configuration interaction. The g values of the levels are found to agree closely with those calculated on the basis of perfect J_j coupling.

© 1962 Optical Society of America

Energy Levels of Er II

Z. B. Goldschmidt
J. Opt. Soc. Am. 53(5) 594-595 (1963)

Level Structure of Singly Ionized Thulium (Tm ii)†

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4f¹²(³H₆)6s6p Levels of Neutral Erbium (Er i)†

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Energy Levels of the First Spectrum of Europium (Eu i)†

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