Stress-induced optical dichroism of V −-centers in MgO

Abstract

The stress-induced optical dichroism and optical absorption spectra of the V −-centers in electron irradiated MgO are reported. The dichroism spectrum can be largely attributed to a paraelastic alignment of inherently-dichroic V −-centers. A curve-fit analysis of the lower-energy portions of the dichroism and absorption spectra yields the ratio of the transition dipole strengths, D ∥ D ⊥ = 1.55 ± 0.2 , and the energy splitting, E ∥ − E ⊥ = 0.22 ± 0.07 eV, for light polarized parallel (∥) and perpendicular (⊥) to the defect symmetry axis. The spectra also have considerable intensity in their high-energy tails, and it is speculated that a portion of this intensity is due to the V-center. The implications of the results with regard to the electronic structure of the center are discussed.