Compositionally homogeneous ZrO2–CeO2 nanopowders have been characterized by Raman and extended x-ray absorption fine structure (EXAFS) spectroscopies. These techniques revealed a tetragonal-to-cubic phase transition as a function of CeO2 content, as observed in a previous synchrotron x-ray diffraction study. The tetragonal–cubic phase boundary was found to be at (85 ± 5) mol% CeO2. The EXAFS study demonstrated that this transition is related to a tetragonal-to-cubic symmetry change of the Zr–O first neighbour coordination sphere, while the Ce–O coordination sphere preserves its cubic symmetry over the whole composition range.

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Poly(2-pyridinium hydrochloride-2-pyridylacetylene) (P2EPH) is a water-soluble conjugated polymer that is fluorescent when excited in the visible region. The problems associated with this fluorescence have been overcome, thus permitting a Raman spectroscopic investigation of P2EPH. The fluorescence was avoided by recording spectra with excitation in the UV region (244 nm); for spectra excited with a visible laser, silver colloids, electrodes and pellets were used to minimize the fluorescent background. The obtained results allowed an improvement in the band assignment of the P2EPH vibrational spectra and strongly suggested a higher content of the non-protonated pyridine moiety than previously reported.

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