Satellite structure in the X-ray photoelectron spectra of some binary and mixed oxides of lanthanum and cerium

Abstract

A study of the core-electron X-ray photoelectron (X-p.e.) spectra of the f o compounds La, O, , LaMO, (M = Fe and Co), CeO,. and BaCeO, is described. Results on the chelate species [La(tmhd),] and [Ce(tmhd),] (tmhd = 2,2,6,6-tetramethylheptane-3,5-dionato) are included for comparison. Special precautions have been taken to ensure an optimal degree of surface purity of the samples. Satellite structure has been observed for the 4p. in addition to the 3d and 4d, signals in both the lanthanum(iii) and cerium(iv) compounds. These satellites are discussed in terms of coexcitations of the charge-transfer type, principally 0 2p + metal 4f transitions. In the cerium(1v) oxides the satellites are apparently due to energy-gain (representing ' shake-down ') rather than energy-

The interaction of oxygen with the surface of CeO2–TiO2mixed systems: an example of fully reversible surface-to-molecule electron transfer

“…45 These particular compositions distinguish the solids here investigated from other systems containing a small concentration of ceria dispersed in the TiO 2 matrix previously studied by other authors. The sol-gel method adopted for the preparation originates complex systems whose main features are resumed in 50 the following. 1.…”

“…Micro-Raman (µ-Raman) spectra were recorded on a Jobin Yvon 50 LabRam HR800 spectrometer, equipped with a He-Ne laser (632.8 nm), connected to an Olympus BX41 microscope. TEM analysis of the powder samples deposited on a copper grid was performed using a Jeol JEM 3010 (300kV) microscope equipped with a EDS detector by Oxford Instruments.…”

“…By the way the oxygen storage capacity (OCS) is greatly enhanced when Zr is introduced in to the cubic ceria structure and in particular upon formation of phases with pyrochlore structure such as Ce 2 Zr 2 O 7 (vide infra) [19][20][21] . The strong optical absorption around 400nm of cerium dioxide 50 (with a weak tail in the visible range capable of imparting a pale yellow colour to the material) has also stimulated studies devoted to the use of this material as a possible photocatalyst 22 .…”

“…In the Ce 3d 5/2 peak, the most intense features are the peaks at 882.7 eV (v) and 888. 50 should be taken into account to draw a thorough picture of this advanced material. The spectrum of Ti 2p core level indicates that titanium is always full oxidized as confirmed by the constant position of the peak maximum at 458.8 eV, which is typical of octahedrally 55 coordinated Ti 4+ ions 54 .…”

Cerium oxide nanoparticles protect against Aβ-induced mitochondrial fragmentation and neuronal cell death

“…The binding energy of the Au (4f7/2) at 84.0±0.1 eV was used to calibrate the binding energy scale of the spectrometer, and ratios of Ce 3 þ and Ce 4 þ in the samples were determined. 62,63 Statistics. Results were collected from three or more independent experiments and are expressed as mean ± S.D.…”