Halogen Bonding in Supramolecular Chemistry.

Giant and isotropic magnetoresistance as huge as −53% was observed in magnetic manganese oxide La0.72Ca0.25MnOz films with an intrinsic antiferromagnetic spin structure. We ascribe this magnetoresistance to spin‐dependent electron scattering due to spin canting of the manganese oxide.

31p-S-4 Giant Magnetoresistance in Magnetic Manganese Oxide with Intrinsic Antiferromagnetic Spin Structure

Calculated Mn(2p3/2) X-ray photoelectron spectra (XPS) of Mn 21 ,M n 31 , and Mn 41 free ions are strikingly similar to Mn(2p 3/2) spectra of Mn 21 -, Mn 31 -, and Mn 41 -oxides and oxyhydroxides, indicating that these ions adopt high spin states in MnO, manganite, and birnessite. The Mn(2p) peak structures reveal the presence of only Mn 31 in manganite, but Mn 21 ,M n 31 , and Mn 41 are present in the near-surface of synthetic birnessite at about 5, 25, and 70%, respectively. Precipitation of birnessite by reaction of Mn 21 (aq) with an

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Interpretation of XPS Mn(2p) spectra of Mn oxyhydroxides and constraints on the mechanism of MnO 2 precipitation

The chemistry of the hydrogen sulfide and iron sulfide systems in natural waters

Vanadium oxide monolayer catalysts Preparation, characterization and catalytic activity

Systematics in the X-ray photoelectron spectra (X. p. e. s.) of Ti, V, Cr, Mn and Nb oxides with the metal ion in different oxidation states as well as of related series of mono-, sesqui- and di-oxides of the first row transi­tion metals have been investigated in detail. Core level binding energies, spin-orbit splittings and exchange splittings are found to exhibit inter­esting variations with the oxidation state of the metal or the nuclear charge The 3d binding energies of the monoxides show a proportionality to Goodenough’s ( R — R c ). Other aspects of interest in the study are the satellite structure and final state effects in the X. p. e. s. of the oxides, and identification of different valence states in oxides of the general formulae M n O 2 n -1 and M 3 O 4 . The nature of changes in the 3d bands of oxides under­-going metal-insulator transitions is also indicated.

Study of transition metal oxides by photoelectron spectroscopy

Surface oxidation of La, Ce, Sm and Tb metals has been investigated by He(II) ultraviolet photoelectron spectroscopy (u.p.s.) and X-ray photoelectron spectroscopy (X.p.s.). Oxidation of La gives rise to La2O3 on the surface. While Ce2O3 appears to be the stable oxide on the surface, we find evidence for formation of CeO2 at high oxygen exposure. Valence band of Sm clearly shows the presence of both divalent and trivalent states due to interconfigurational fluctuation. Exposure of Sm to oxygen first depletes the divalent Sm at the surface. While Sm2O3 is the stable oxide on the surface of Sm, Tb2O3 is the stable oxide on the surface of Tb (and not any of the higher oxides).

Study of surface oxidation of rare-earth metals by photoelectron spectroscopy

L$\_{23}$ M$\_{45}$ M$\_{45}$/L$\_{23}$ M$\_{23}$ M$\_{45}$, L$\_{23}$ M$\_{45}$ M$\_{45}$/L$\_{23}$ M$\_{23}$ M$\_{23}$ and L$\_{23}$ M$\_{23}$ M$\_{45}$/L$\_{23}$ M$\_{23}$ M$\_{23}$ Auger intensity ratios in transition metal oxides and sulphides are shown to be directly related to the number of valence electrons in the metal as well as to its oxidation state. The metal Auger intensity ratios provide a unique probe, independent of O (KLL) intensity, to study surface oxidation states of metals. These intensity ratios have been effectively employed to investigate surface oxidation of nickel, iron and copper. The oxidation studies have unravelled some interesting aspects of surface oxidation.

A Novel Approach to the Study of Surface Oxidation States and Oxidation of Transition Metals by Auger Electron Spectroscopy

Several oxide systems were investigated in an effort to explore for the presence of O (2p) VB holes forming peroxide-type units, relevant to the mechanism of metallicity as well as high-temp. supercond. in oxides such as $YBa_2Cu_3O_7-\delta$. Photoelectron spectroscopy was used to delineate O2- and O22- species in the metal oxides. Most interesting, though unexpected results were obtained, which are of considerable significance to the structure and properties of metal oxides. Typical of the oxides examd. are $BaPbO_3$, $La_2NiO_4$, and $YBa_2Cu_3O_7$.

Holes in the oxygen (2p) valence bands and the concomitant formation of peroxide-like species in metal oxides: their role in metallicity and superconductivity

M.S. Hegde

Papers

Study of transition metal oxides by photoelectron spectroscopy

Study of surface oxidation of rare-earth metals by photoelectron spectroscopy

A Novel Approach to the Study of Surface Oxidation States and Oxidation of Transition Metals by Auger Electron Spectroscopy

Holes in the oxygen (2p) valence bands and the concomitant formation of peroxide-like species in metal oxides: their role in metallicity and superconductivity

Surface oxidation of cadmium, indium, tin and antimony by photoelectron and Auger spectroscopy