=+1 m=+2 B m=+1/2 m=0 m=0 m=-1/2 1三一 I=1/2 与外磁场平行，能量较低，m=+1/2,E12=一uH0 1=1/2的氢核 与外磁场方向相反，能量较高，m=-1/2,E.12=μH0 I = 1/2 I = 1 I = 2 m = − 1/2 m = +1/2 m = − 1 m = +1 m =  m = − 2 m = − 1 m =  m = + m = + z z z B0 与外磁场平行，能量较低，m=+1/2, E 1/2= －H0 与外磁场方向相反, 能量较高, m= -1/2, E -1/2=H0 I=1/2的氢核