The Zeeman effect in the [17.6]7.5-X18.5 transition of holmium monoxide

► Study of Zeeman effect on individual hyperfine lines in HoO [17.6]7.5-X18.5 transition. ► Asymmetric Zeeman splitting in P(8.5) due to interaction of hyperfine levels. ► Effective g-factors (geff) indicate electronic transition 6H7.5-6I8.5. ► J-dependent geff shows 6H7.5J = 7.5 level probably has small contribution from a 6I7.5 state.