“…In their as-deposited state (after air exposure), the films show only peaks corresponding to Ta-oxides (Ta4f 7/2 at 26.2 ¡ 0.2 eV). 43,52,[55][56][57] As expected for very thin Ta films after ambient air exposure, 33,52 oxidation of the entire films is confirmed and no peaks corresponding to Ta-metal (Ta4f 7/2 y22 eV) or Ta-carbide (Ta4f 7/2 y23.3 eV) are found. 43,52,[55][56][57] When heated in vacuum, the thin Ta-oxide on SiO 2 support does not change its chemical state, i.e., it stays oxidised even at 850 uC (Fig.…”