In Situ Raman Spectroscopy of RuO 2 ·xH 2 O

. To investigate the origins of the Raman peaks, isotope effects were studied using deuterated samples. Most of the Raman peaks showed no shift due to the heavier mass of deuterium, indicating that these peaks do not come from vibrations that involve hydrogen ions. Based on the changes in the Raman spectra, we conclude that the major effect upon intercalation of hydrogen is reduction of Ru 4+ ions to Ru 3+ , and not creations of new chemical bonds.