The mass spectra of both positive and negative charged Ta-containing ions from laser ablatiou of Ta2O5 were measured using a time-of-flight mass spectrometer. Formation of iomc Ta-containing oxides such as TaO and TaO from Ta2O5 ablation in ambient O2 were observed for the first time. The influence of ambient O2 pressure on the intensities of ablated Ta-containing ions has also been studied. It is found that the subsequent oxidation reactions were involved in the ablation of Ta2O5 at different O2 pressure. The enthalpies of possible okidation reactions were theoretically calculated, and the possible formation reastions of the ionic Ta-contauing oxides are discussed.
