Optical absorption of MgO:Mn

Abstract

Wavelength-modulated absorption measurements on MgO:Mn show the presence of Mn³⁺ and Mn²⁺. The lowest spin-allowed transition of Mn³⁺ occurs at 520 nm. Weak bands at 301, 356, 389 and 426 nm are attributed to transitions from ⁶A_1g to the ⁴T_1g(P), ⁴T_2g(D), ⁴E_g(G)+⁴T_2g(G) and ⁴T_2g(G) states of Mn²⁺, respectively. The latter band shows four zero-phonon lines with an over-all splitting of 34 cm^-1 revealing a spin-orbit splitting of the ⁴T_2g(G) state reduced by a factor of four by the action of a dynamic Jahn-Teller effect. Stress experiments indicate that the dominating Jahn-Teller interaction is with T₂ symmetry vibrations.