Abstract
The two entire structures of the 10 odd levels 4f 11(4 I 15/2)5d and 6 even levels 4f 11(4 I 15/2)6p of Ho II have been established. Forty infrared lines are classified. The following values for the spin-orbit parameters have been obtained directly from the two structures based on their evident J-j character: ζ5d = 802 cm-1, ζ6p = 2 118 cm-1