ゼーマン効果
A similar removal of degeneracy will occur when a paramagnetic molecule is placed in a magnetic field, an instance of the Zeeman effect. Most species which can be observed in the gaseous state are diamagnetic . Exceptions are odd-electron molecules such as nitric oxide, NO, nitrogen dioxide, , some chlorine oxides and the hydroxyl radical. The Zeeman effect has been observed with dioxygen,