Abstract

Modes of internal vibration of the phosphate ion PO43- at a Td symmetry and at a site having D2d symmetry are derived from group-theory calculations. The micro-Raman spectra of some orthophosphates activated with Eu3+ were recorded. The splitting of spectral bands of these orthophosphates shows that the phosphate ion is placed in a crystal on a site of symmetry less than Td such as D2d, the local crystal field may lift some or all of degeneracy of the Raman bands. The results of the current paper show that all of them are lifted totally. The ab initio calculations at level HF with basic set 6-31++G(d) have affirmed above.