Showing papers by "Frank S. Stone published in 1985"
TL;DR: In this paper, the merits of UV-visible diffuse reflectance spectroscopy for the study of surface phenomena on microcrystalline MgO, CaO and SrO are described and illustrated.
30 citations
TL;DR: In this article, the steric effects on lattice distortion are discussed alongside the covalent contribution in the metal-oxygen bonds, which is manifested in the strong tetrahedral preferences of Cd2+ and Ga3+ ions.
Abstract: CdGa2O4, CuGa2O4 and four ternary spinels CdxCu1–xGa2O4 have been prepared by solid-state reaction of mixtures of CdO, CuO and Ga2O3 at 1223 K. X-ray powder diffractometry has been used to determine the unit-cell parameter, a0, the oxygen parameter, u, and the respective distributions of Cd2+, Cu2+ and Ga3+ in tetrahedral and octahedral coordination, by applying a computational method to compare observed and calculated diffraction intensities. The capability of the method has been tested for CuGa2O4, where the Cu2+(3d9) and Ga3+(3d10) ions have similar scattering powers, by comparing the results with data from neutron diffraction.CdGa2O4 and CuGa2O4 are 15 and 84% inverse, respectively. Interdependence of a0, u and the cation distribution is closely analysed for CdxCu1–xGa2O4, where the behaviour of the ternary system gives new insight into the oxide crystal chemistry. The steric effects on lattice distortion are discussed alongside the covalent contribution in the metal–oxygen bonds, which is manifested in the strong tetrahedral preferences of Cd2+ and Ga3+ ions.
19 citations
TL;DR: Ammonia adsorption on well-outgassed Mg0, Ca0, and Sr0 generates UV bands which extend the absorption edge due to excitation at surface jons from ∼40,000 cm −1 (Mg0), 35, 000 cm − 1 (Ca0) and 32,000cm − 1(Sr0) to 25,000 km- l as mentioned in this paper.
Abstract: Ammonia adsorption on well-outgassed Mg0, Ca0 and Sr0 generates UV bands which extend the absorption edge due to excitation at surface jons from ∼40,000 cm −1 (Mg0), 35,000 cm −1 (Ca0) and 32,000 cm −1 (Sr0) to 25,000 cm- l . The effects of dissociative adsorption, producing M 2+ -NH −2 (and OH-) species at low-coordinate M 2+ -O 2 - sites, are distinguishable from those of non-dissociative reversible adsorption. The latter produces bands extending t o 25,000 cm- 1 and these are ascribed to a surface analogue of charge-transfer-to-solvent (ctts) spectra, generated as NH 3 molecules envelop NH 2 − ions and the residual surface O 2- ions.
5 citations
01 Jan 1985
TL;DR: In this article, Giamello et al. reported the reactivity and spectral features of CO and NO on particularly reactive sites of MgO a paramagnetic species, which has been recently characterized by infrared spectroscopy and electron paramagnetic Resonance Spectroscopy.
Abstract: CO and NO form on particularly reactive sites of MgO a paramagnetic species, which has been recently characterized by infrared spectroscopy and electron paramagnetic resonance spectroscopy (E. Giamello et al., to appear in J. Chem. Soc. Faraday Trans. I (1984)). New data are reported about the reactivity and spectral features. Labelling of the oxygen in CO provides evidence about the structure of the species, and two possible models are discussed.
4 citations