Raman spectroscopy provided additional insights into the structural changes. The Raman spectra of TMC films, excited with a 785 nm laser (see Figure ), revealed distinct regions corresponding to Ti, C, and surface groups: in-plane vibrations of surface groups attached to Ti atoms (230-470 cm -1 ) and C vibrations (580-730 cm -1 ). After plasma treatment, the ratio between the E g (T x =O) and A 1g (Ti, C, O) peakscorresponding to =O surface terminations and bulk vibrations, respectively-increased from 0.79 to 0.88, which is consistent with the XPS results, further confirming the effectiveness of the plasma-ALE process.