EPR measurements indicate that the electronic environment of Cu~(2+) ion in BaCuSi_4O_(10) is of axial symmetry. At a glance,this contradicts the optical absorption spectrum in which four bands are observed.

• 在这种对称性下,一般只能观察到三条Cu~(2+)离子的吸收谱带,但在BaCuSi_4O_(10)的吸收谱中却观察到了四条。