X-ray absorption studies ofCeO2,PrO2, and

H. De×pert

¹

,

R.C. Karnatak

²

,

J.M. Esteva

³

et al.

Valence of Highly Dispersed Cerium Oxide Species on Silica Quantitatively Estimated by Ce L<SUB>III</SUB>-edge XANES

“…It can be considered that CeO 2 is an insulating mixed valence or interatomic intermediate-valence system having a mixture of multielectrons configurations 4f 0 and 4f 1 in the ground state. 12,13) But it does not close any other possibilities that the B 0 peak might be formed due to a delocalization of 4f state 14) or a slight reduction of the oxide by the intense photon beam in experiment. 12) Figure 3 shows powder X-ray diffraction patterns of the samples.…”

“…Ce L III -edge XANES spectroscopy has been proposed as a useful method for the quantitative determination of the ratio of Ce(III) and Ce(IV), since both species exhibit each distinguishable absorption peaks. [10][11][12][13][14][15][16][17][18][19][20][21][22] In the present study, a series of SiO 2 -CeO 2 samples were prepared by impregnation method followed by calcination in air and studied by Ce L IIIedge XANES through a curve fitting analysis in order to know the ratio of Ce(III) and Ce(IV) and assignment of the UV absorption band for these species on silica.…”

A Macrocyclic Chelator That Selectively Binds Ln4+ over Ln3+ by a Factor of 1029

“…Although the excited states probed by L 3-edge and M5,4-edge XANES have very different electronic configurations, recent studies have proposed that both are sensitive to 4f orbital occupation. 7,12,[17][18][19]22,[24][25][26][154][155][156][157] However, the role of final state effects including core-hole induced changes in 4f occupancy, and other physical phenomena, remains controversial and is the subject of a persistent debate. 18,33,[35][36] Figure 8 compares the background-subtracted and normalized Ce L3-edge XANES spectra of CeLK4 and reference compounds CeO2, 158 [Et4N]2[CeCl6], 57 and (C8H8)2Ce.…”

“…99 Each of the L3-edges exhibited a double-peak structure that is characteristic of published data for formally Ce 4+ compounds such as CeO2, Ce(SO4)2, and CeF4. 7,[17][18] The double-peak structure observed in Ce L3-edge XANES spectra is often taken to reflect the presence of a configuration interaction of the main, ionic 4f 0 configuration and a LMCT configuration, 4f 1 L, where L represents a ligand hole. Differences in screening of the 2p core hole by the 4f orbitals results in the large splitting between 4f 1 L5d 1 and 4f 0 5d 1 final states that is observed in the L3-edge spectra.…”

“…Cerium can be found in the +4 formal oxidation state in some non-molecular, extended solids such as Cs2CeCl6 and other binary halides, [3][4][5][6] CeO2, 7 Ce(SO4)2, 8 and [NH4]2[Ce(NO3)6], 9-10 among others. 11 These materials have been the subject of numerous synchrotron radiation based spectroscopy experiments, including X-ray photoelectron spectroscopy, 12 resonant inelastic X-ray scattering, 13 and X-ray absorption spectroscopies at the cerium L3, [7][8][14][15][16][17][18][19][20][21][22] M5,4-, 12,19,[23][24][25][26][27][28][29][30] and N5,4-edges, 12 as well as ligand K-edges. [31][32] Some of these studies have presented evidence for the importance of both 4f and 5d orbital contributions to covalency in Ce bonding.…”