Electron energy loss spectra of Na0.33CoO2.yH2O (y = 0, 0.6 and 1.3)
  Electron energy loss (EEL) spectra have been obtained on materials with the nominal compositions of Na0.33CoO2_yH2O (y = 0, 0.6 and 1.3). Spectral analyses revealed systematic changes in the low-loss energy region (< 10eV) and the core losses(O-K, Co-L3,2) along with the water intercalation. The inter (intra)-band transitions and the relevant plasmon resonance were found to be sensitive to water content. Variations of the electronic structure and the Co valence states during hydration have been discussed based on our experimental results. 
J.Q. Li, H.X. Yang, R.J. Xiao, Y.G. Shi and H.R Zhang