Table 3. Experimental First dd-Excitation and its Relation to Different 10Dq Values and Δ.

	first dd	10Dqeff	10Dqion	ΔECT	Δ
CoF2	0.85	0.92	0.70	0.22	8.8
CoCl2	0.77	0.81	0.47	0.34	3.6
CoBr2	0.71	0.75	0.38	0.37	2.4
CoS	0.67	0.70	0.29	0.41	0.8