Raman spectra of titanium dioxide (anatase, rutile) with identified oxygen isotopes (16,17,18)

Six representative isotope-labeled samples of titanium dioxide were synthesized: (TiO2)-O-16, (TiO2)-O-17 and (TiO2)-O-18, each in anatase and rutile forms. Their Raman scattering was analyzed at temperatures down to 5 K. Spectral assignment was supported by numerical simulation using DFT calculations. The combination of experimental and theoretical Raman frequencies with the corresponding isotopic shifts allowed us to address various still-open questions about the second-order Raman scattering in rutile, and the analysis of overlapping features in the anatase spectrum.