Correlation between (formula presented) and oxygen arrangement of the charge reservoir block in (formula presented) a raman study

The polarized Raman spectra of (Formula presented) and their variations upon removal of oxygen were studied. The observed Raman lines at 117, 144, 160, 265, 381, and (Formula presented) for the as-prepared samples were assigned to definite atomic vibrations. It was found that the increase of (Formula presented) with the withdrawal of oxygen correlates with changes of the phonon mode frequencies and with appearance and enhancement of a Raman band near (Formula presented) The latter band decreases again with further reduction of the oxygen content. The results are discussed within a model accounting for the oxygen out-diffusion from the chain sites in the (Formula presented) charge reservoir layer in close comparison with earlier reports on the variations with laser annealing of the Raman spectra of (Formula presented)