Symmetry-based vibrational analysis of polyatomic ionic species in polymer electrolytes:: Application to the compounds poly(ethylene oxide)3LiCF3SO3 and poly(ethylene oxide)NaCF3SO3

A symmetry-based vibrational analysis of the compounds (PEO)(3)LiCF3SO3 and (PEO)NaCF3SO3 is described which preserves the distinct identity of the CF3SO3- intramolecular vibrational modes in the one-dimensional and three-dimensional space groups appropriate to each compound. The infrared and Raman spectra in the delta (s)(CF3) spectral region of the two compounds are discussed in terms of this formalism, although a similar analysis of the nu (s)(SO3) region is limited to the (PEO)(3)LiCF3SO3 compound. ii one-dimensional space group is sufficient to describe the delta (s)(CF3) spectral region in both compounds and the nu (s)(SO3) region in (PEO)(3)LiCF3SO3.