spin orbit coupling

The magnitude of "spin orbit coupling" is different depending on whether the electron spin is parallel or anti-parallel to the orbital shell spin l, thus the two states possess different energies. In 2p electrons, L₂ (total angular momentum j = l - s = 1/2) and L₃ (total angular momentum j = l + s = 3/2) are formed. In an EELS spectrum of transition from the 2p occupied state to the 3d unoccupied state (band), L₃ and L₂ peaks sequentially appear in the energy-loss order of low to high. It should be noted that those peaks provide information on the energy splitting of the occupied state (several eV to 20 eV) but does not provide information on the unoccupied state expected by EELS. However, the intensity ratio of L₃ to L₂ varies from 2:1 due to the effect of the expected chemical-bonding state in the unoccupied state. When the experimental intensity profile is compared with theoretical calculations, information on the valence of 3d electrons is obtained, where the calculations must take account of the effect of core-hole interaction, correlation between 3d electrons and valences. The intensity ratio of L₃ to L₂ tends to be large at the high spin state whereas small at the low spin state.

Related Term(s)