电偶极跃迁 中=-eE·x=-D· E cos ot ex(e<o) Absorption 2A(D. Eomk[ S[Em(Em+ho) zele 2h lxmkI cos 0 S[Em -(Em +ho)I 0=angle of(d,eo) <cos2b>=1/3电偶极跃迁 cos 1/ 3 ( , ) cos [ ( )] 2 ( ) [ ( )] 2 ( 0) ' cos 2 0 2 2 2 0 2 2 0 0  = = = − +   − + =  = = −  = −                 angle of D E x e E w D E Absorption D ex e H e eE x D E t m k m m m k m k m m               