All lanthanide Ln2+/Ln3+ pairs have the same InterValence-Charge-Transfer absorption onset (Ln2+ + Ln3+ + https://t.co/kdwyspiR7v -> Ln3+ + Ln2+) in a given host, regardless of what's the lanthanide; Ce=Pr=Nd=...=Yb. https://t.co/zpf3027s8P https://t.co/zpf3027s8P