Crystal-Field Splitting Effect on the Vibrations of Polytetraphosphate Anion in the AgGd(PO_3)_4 Crystal

摘要

The fundamental vibrations of the (PO_3)_4 anions in the AgGd(PO_3)_4 crystal are predicted by employing the correlation method based on the group theory. Nine external vibrations are allowed with no coincidence activity between infrared and Raman spectra. The free PO_3 ion with C_(3V) molecular symmetry has six normal vibrations. Due to the crystal-field splitting effect, the six normal modes of vibrations are split into 96 intramolecular vibrations. Symmetric and asymmetric stretching and bending modes are identified with determining of their spectral activity.