A spin state is denoted by a vertical arrow. The double down-
wards arrow, the double upwards arrow and the zero represent,
respectively, the states mS ¼ 1, 1 and 0 of the electron spin-1, the
single downwards arrow and the single upwards arrow the states
ms ¼ 21 and 21 of the electron spin-21 . The eigenvectors identify
with the basis states fjmSms〉g since the four off-diagonal elements,