Fifteen Cr4+ local modes are observed using resonance Raman scattering in a Cr:Mg<thin>2SiO4 crystal, instead of a maximum of nine internal vibrations predicted by first neighbor interactions. The larger-than-predicted number of modes is explained in terms of second neighbor interactions for the Cr4+ ion. The frequency dependence of the two tetrahedral stretching modes measured at 361 and 765 cm-1 on second neighbor parameters shows a different degree of localization at the Cr<thin>4+ site for these modes.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)