Symmetry Considerations in the Spectrum of Ruby

摘要

The role of the point symmetry of the Cr3plus;ion in the spectral analysis of Cr3plus;in Al2O3is reviewed. Previous energyhyphen;level calculations were made on the basis ofC3vsymmetry with a reflection plane perpendicular to the unique axis. Little change in the gross spectral features is expected ifC3(noninversion center) operators are used. However, as noted by McClure, it is necessary to go toC3(NIC) when calculating electric dipole radiation matrices. For consideration of the axial optical and microwave electric effects it is sufficient to considerC3v(NIC). For the full microwave electric effect tensor,C3(NIC) must be used. The interelations between the electric effects and the optical radiation dipole operators are explored. A substantial contribution to the ruby4A2groundhyphen;state splitting 2Dis expected from the ``odd NIC fields.'' The magnitude of this effect for Cr2O3is considered.