Configurations 4fN^–16s^26p in Neutral Gadolinium, Dysprosium, Erbium, and Ytterbium*

The groups of six levels obtained by adding, in J–j coupling, a 6p electron to the lowest level of the 4fN–1 core have been identified in gadolinium, dysprosium, erbium, and ytterbium (N=8, 9, 12, 14). They account for strong transitions to the corresponding 4fN–15s6s2 configurations. Values for the spin–orbit parameter of the 6p electron are (in cm−1) ζp=1835, 1840, 2049, 2257, respectively.