Polarized Raman and infrared vibrational analysis of (VO)2P2O7 single crystals

Abstract Single crystals of the low dimensional spin system compound (VO) 2 P 2 O 7 were studied by polarized Raman spectroscopy and FT-IR spectroscopy in the spectral range 100– 1400 cm −1 . Characteristic groups of modes were compared with literature data of structurally related compounds. Though some differences to vibrational spectra of the referred compounds were detected, we achieved a satisfactory assignment of most of the high-energy modes to vibrations of the P 2 O 7 polyhedra and the VO 5 pyramids. In particular, we report the observation of an unusual softening of the prominent V=O vibration which we explain by the interlayer interaction of neighboring V and O atoms—an effect, which has been observed in NaV 2 O 5 , as well.