Raman scattering study of in the charge disordered and ordered phases

Polarized Raman spectra of sodium vanadium oxide η - Na 1.3 V 2 O 5 single crystals were measured over wide temperature and frequency ranges. In total 27 first-order Raman modes, as well as overtones and combinational lines, are observed. For the charge ordered phase no appearances of new phonon- or spin-related Raman modes are registered on lowering the temperature to 10 K. The phase transition at about 100 K is manifested through an abrupt change of the phonon mode frequencies and dampings.