When Ta-coated quartz surface was subjected to XPS analysis, C(1s) peak was observed at 288.6 eV, shift was found to be +4.1 eV. Ta(4f7/2) and Ta(4f5/2) peaks were obtained at 32.0 eV and 34.0 eV, respectively. The relevant XPS spectrum is shown in Fig. 2(c). By subtracting the C(1s) shift from these values, corrected Ta(4f7/2) and Ta(4f5/2) peaks were found to be at 27.9 eV and 29.9 eV, respectively. The literature values for Ta(4f) XPS signal were 26.8 eV for Ta2O5 and 28.0 eV for TaF5[30]. The oxidation state of Ta on quartz surface could be +5.