In an effort to reconcile the various interpretations for the cation components of the 2p _3/2 observed in x-ray photoelectron spectroscopy (XPS) of several spinel oxide materials, the XPS spectra of both spinel alloy nanoparticles and crystalline thin films are compared. We observed that different components of the 2p _3/2 core level XPS spectra, of these inverse spinel thin films, are distinctly surface and bulk weighted, indicating surface-to-bulk core level shifts in the binding energies. Surface-to-bulk core level shifts in binding energies of Ni and Fe 2p _3/2 core levels of NiFe₂O₄ thin film are observed in angle-resolved XPS. The ratio between surface-weighted components and bulk-weighted components of the Ni and Fe core levels shows appreciable dependency on photoemission angle, with respect to surface normal. XPS showed that the ferrite nanoparticles Ni _x Co_1−x Fe₂O₄ (x = 0.2, 0.5, 0.8, 1) resemble the surface of the NiFe₂O₄ thin film. Surface-to-bulk core level shifts are also observed in CoFe₂O₄ and NiCo₂O₄ thin films but not as significantly as in NiFe₂O₄ thin film. Estimates of surface stoichiometry of some spinel oxide nanoparticles and thin films suggested that the apportionment between cationic species present could be farther from expectations for thin films as compared to what is seen with nanoparticles.

中文翻译：

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对某些反尖晶石氧化物中阳离子的 2p 3/2 核心能级 X 射线光电子能谱成分的解释

为了协调对 2 种阳离子成分的不同解释p _3/2在几种尖晶石氧化物材料的 X 射线光电子能谱 (XPS) 中观察到，比较了尖晶石合金纳米粒子和晶体薄膜的 XPS 光谱。我们观察到 2 的不同组成部分p 这些反尖晶石薄膜的_3/2核心能级 XPS 光谱具有明显的表面和体积加权，表明结合能的表面到本体核心能级的变化。 Ni 和 Fe 2 结合能的表面到体核能级变化p _{在角度分辨XPS中观察到NiFe 2} O ₄薄膜的_3/2核心能级。 Ni 和 Fe 核心水平的表面加权成分与体积加权成分之间的比率显示出对相对于表面法线的光电发射角的明显依赖性。 XPS表明铁氧体纳米颗粒Ni _X 钴_1−X Fe ₂ O ₄ (X_{= 0.2, 0.5, 0.8, 1) 类似于NiFe 2} O ₄薄膜的表面。在CoFe ₂ O ₄和NiCo ₂ O ₄薄膜中也观察到表面到块体芯能级移动，但不如在NiFe ₂ O ₄薄膜中显着。对一些尖晶石氧化物纳米粒子和薄膜的表面化学计量的估计表明，与纳米粒子所观察到的情况相比，存在的阳离子物种之间的分配可能与薄膜的预期相差更远。