The surface oxidation behaviors of UN_0.68 and UN_1.66 thin films are investigated by X-ray photoelectron spectroscopy (XPS), and the traditional U4f/N1s, O1s, valence band spectra as well as the unconventional U4d and U5d spectra are collected for the understanding of their oxidation behavior in-depth. Similar asymmetrical peak shape of the U4f spectra to uranium is observed for both uranium nitrides, despite of a slight shift to higher energy side for UN_1.66 clean surface. However, significant difference among the corresponding spectra of UN_0.68 and UN_1.66 during oxidation reveals the distinctive properties of each own. The coexistence of UO_2-x, UO₂ and UO_2-x.N_y on UN_0.68 surface results in the peculiar features of U4f spectra as well as the others within the XPS energy scale, where peaks of the oxidized species firstly shift to higher energy side compared to the clean surface, and then return closely towards those of stoichiometric UO₂. For UN_1.66, the generation of U-N-O ternary compounds on the surface is identified with the symmetrical U4f peaks at 379.9eV and 390.8 eV, which locate intermediate between UO₂ and UN_1.66, and gradually expanding to higher energy side during the progressive oxidation. Furthermore, the formation of N-O species on UN_1.66 surface is also detected as an oxidation product. The metallic character of UN_1.66 is identified by the intense signal at Fermi level, which is greatly suppressed by the increasing oxygen exposure and implies the weakening metallic properties of the as-generated U-N-O compounds. Higher uranium oxides, such as UO₃ and U₄O₉, are deduced to be the final oxidation products, and a multistage mechanism for UN_1.66 following the exposure to oxygen is discussed.

通过X射线光电子能谱（XPS）研究了UN _0.68和UN _1.66薄膜的表面氧化行为，并收集了传统的U4f / N1s，O1s，价带光谱以及非常规的U4d和U5d光谱，以供理解。对它们的氧化行为进行了深入研究。对于两种氮化铀，都观察到U4f谱图与铀具有相似的不对称峰形，尽管对于UN _1.66清洁表面，其向较高能级的偏移很小。但是，在氧化过程中，UN _0.68和UN _1.66的对应光谱之间的显着差异揭示了它们各自的独特特性。UO _2-x，UO ₂和UO的共存在UN _0.68表面上的_2-x .N _y会导致U4f光谱以及XPS能量范围内的其他特征的特殊特征，其中氧化物种的峰首先移至与清洁表面相比较高的能量侧，然后返回接近化学计量的UO ₂。对于UN _1.66，可以在表面上生成UNO三元化合物，其对称的U4f峰位于379.9eV和390.8 eV，位于UO ₂和UN _1.66之间，并在逐步氧化过程中逐渐扩展到较高的能量侧。此外，在联合国_1.66上形成NO物种表面也被检测为氧化产物。UN _1.66的金属特征通过费米能级的强信号来识别，该信号被增加的氧气暴露量大大抑制，这意味着刚生成的UNO化合物的金属性能会减弱。可以推断出诸如UO ₃和U ₄ O _9之类的高级铀氧化物是最终的氧化产物，并讨论了在暴露于氧气后UN _1.66的多级机理。