Review—Similarity of 3 <i>d</i> <sup>3</sup> (Mn <sup>4+</sup> , Cr <sup>3+</sup> )-Ion Luminescence with Raman Scattering Spectroscopy
Sadao Adachi
Abstract
A discussion is given on 3 d 3 (Mn 4+ , Cr 3+ )-ion luminescence properties in various host materials in connection with inelastic light scattering spectroscopy such as Raman and Brillouin scattering. It is shown that the 2 E g → 4 A 2 g luminescence for the intra-3 d 3 -shell electrons can be formulated in a form that is quite equivalent to the inelastic light scattering. A comparison of some 2 E g → 4 A 2 g luminescence features, e.g., the temperature dependence of the anti-Stokes to Stokes intensity ratio, with those of Raman scattering shows very similarity between them. However, no clear similarity can be found between the 4 T 2 g ↔ 4 A 2 g emission/absorption and inelastic light scattering features theoretically nor experimentally. Such differences in similarity or dissimilarity of the intra-3 d 3 -shell transition features with the inelastic light scattering may come from the different spectral dispersion features of the 2 E g and 4 T 2 g states against Dq (or Dq / B ) in the Tanabe−Sugano energy-level diagram thus further promising the electron−lattice interaction to be described by the conventional first-order (one-phonon band) or multi-order (combination band) perturbation theory for the former case (i.e., 2 E g -related luminescence and inelastic light scattering) and by the Franck−Condon principle within the configurational-coordinate model for the latter case ( 4 T 2 g -related luminescence/absorption).