H.O. Perkins

The X-ray photoemission spectra of Nd(OH)3, Sm(OH)3, Eu(OH)3 and Gd(OH)3

Abstract Experimental XPS spectra of lanthanide trihydroxides (Ln(OH)3, where Ln is Nd, Sm, Eu or Gd) at Ln3+5p, 5s, 4d, 4p, 4s, and 3d and OH− 2σ, 3σ and 1π levels are reported. A process of computation obtained by combining Wendins quasi-particle method and the Johansson-Martenssen method with first-order correction is employed in this work to explain the observed physical phenomena. The derived model implies that the spectral function of a long lifetime quasi-particle is a Gaussian function, locates the atomic orbital energy, corrects the variation in binding energy due to the correlation energy, calculates semi-empirically the dipole relaxation energy shift, and accounts for the atom-to-solid core level shift. Valence band XPS spectra, Ln3+ 4d, 4p, 4s, 3d and experimental and theoretical binding energies of Nd3+, Sm3+, Eu3+ and Gd3+ in Ln(OH)3 are tabulated. It is conspicuous that the 4f and 5d orbital collapses are responsible for the interesting features of three giant Coster-Kronig fluctuations, 5 s 1 ⇌ 5 p 2md1 (m = 5, 6, 7, …), 4 p 1 ⇌ 4 d 2mf1 (m = 4, 5, 6, …) and 4 s 1 ⇌ 4 p 14 d 1mf1 (m = 4, 5, 6, …), and the “satellite complex” in the 3d core hole spectra.

Structure of dichromate-type lead pyrophosphate, Pb2P2O7

Abstract Lead pyrophosphate, Pb2P2O7, crystallizes in the triclinic space group P 1 (Z = 4) with a = 6.914(2), b = 6.966(2), c = 12.751(4) A; α = 96.82(3), β = 91.14(3), γ = 89.64(3)°; and V = 612.0(6) A3. Structural refinement data were collected using an automated diffractometer with MoKα radiation. The lead pyrophosphate structure was refined by a full matrix to an R of 0.069 (Rw = 0.067) using 2637 unique reflections. The structure has two unique diphosphate groups that are repeated by lattice translations to form sheets of diphosphate groups. The P2O7 groups, dichromate type, are eclipsed to within 9.4 and 13.5°. The Pb2+ ions are eight- and nine-coordinated to oxygen atoms with average experimental interatomic distances of 2.695 and 2.767 A, respectively.

Synthesis and structural study of samarium hexacyanoferrate (III) tetrahydrate, SmFe(CN)6•4H2O

Abstract Single crystals of SmFe(CN) 6 ·4H 2 O prepared from an aqueous solution under ambient conditions have been used for single-crystal diffraction, thermal gravimetric analysis, and infrared spectrometric studies. This characterized compound is compared to previously reported LnT(CN) 6 (T =Cr, Fe, Co) structures. Samarium hexacyanoferrate (III) tetrahydrate is found to be monoclinic, not hexagonal or orthorhombic as presupposed. SmFe(CN) 6 ·4H 2 O crystallizes in space group P2/ 1 m (No. 11), a = 7.431(1), b = 13.724(3), c = 7.429(2) A˚, β = 119.95(1)°, Z = 2 . Full-matrix least-squares refinement has yielded the final values of R = 0.0292 and R w = 0.0296 for 1028 unique reflections. The observed and calculated densities are 2.198(3) and 2.197 Mg m −3 , respectively. The dominant feature of the structure is that the samarium ion is eight-coordinated, not nine as previously believed. The samarium ion is bonded to six cyanonitrogen atoms and two water molecules in a square antiprism geometry ( D 4d ), the SmN 6 (H 2 O) 2 group. The FeC 6 group is octahedrally arranged. Cyanide bridging links these groups to build an infinite polymeric array. Additional water molecules are trapped in distorted cubic cages within the structure. The important averaged bond lengths are: Sm N = 2.505(15); Sm O = 2.402(1); Fe C = 1.931(3); and C N = 1.156(1)A˚.

A structural investigation of praseodymium potassium hexacyanoferrate (II) tetrahydrate, PrKFe(CN)6 · 4H2O

Abstract Single-crystal and powder X-ray diffraction data, thermal gravimetric analysis, and infrared spectral data are present for PrKFe(CN)6 · 4H2O. The crystal structure has been determined by single-crystal diffractometry and refined by the least-squares method to yield R = 0.0149 and Rw = 0.0155. The praseodymium ions are linked nonlinearly to the FeC6 octahedra by cyanide bridges. Cavities within the structure are occupied by potassium ions and zeolitic water molecules which are within hydrogen bonding distance to the water molecules which are bonded to the nine-coordinated praseodymium ions, PrN6(H2O)3. The powder diffraction data obtained by employing a Siemens Debye-Scherrer camera have yielded cell parameters of a = 7.374(2) and c = 13.816(3)A. The compound is hexagonal, P6 3 m (No. 176), DM = 2.34(3) Mg m−3, and DX = 2.368 Mg m−3. The powder diffraction data have been evaluated and the resultant quantitative figures of merit are F30 = 30(0.021, 48) and M20 = 29.7. Important bond lengths are: PrN = 2.540(3); FeC = 1.908(3); PrO = 2.704(4); and CN = 1.159(4) A.

The X-ray photoemission spectra of La(OH)3

Abstract Experimental X-ray photoelectron spectra of lanthanum at La3+ 5p, 5s, 4d, 4p, 4s, and 3d and OH− 1σ, 2σ, 3σ, and 1π levels are reported. An arithmetic method derived from a combination of Wendins quasi-particle model and the Johansson-Martensson model with first-order correction, is developed to explain the physical phenomena observed in this work. The developed working model suggests that the spectral function of a long lifetime quasi-particle coupled with non-lifetime broadening is a Gaussian function, locates the atomic orbital energy, accounts for the atom-to-solid core level shift and corrects the small variation in binding energy caused by the correlation energy. The spectral function also determines the pure solid state energy shift when the correlation energy of the studied atom or ion is known and calculates semi-empirically the dipole relaxation energy shift. Based on this arithmetic method, La3+, 4d1, and 3d1 and OH− 1σ1, 2σ1, 3σ1, and 1π1 holes are normal quasi-particles having a minimal amount of the dipole relaxation energy shift. However, La3+ 5s1, 4p1 and 4s1 holes are quasi-particles that are severely distorted by the dipole relaxation energy shift, ΣCD (eCA). The ΣCD (eCA) values of La3+ 5s1, 4p1, and 4s1 holes are 3.59(28), 11.58(28), and 11.24(28) eV, respectively.

The structural analysis of NdKFe(CN)6·4H2O

The title compound crystallizes in the hexagonal space group P63/m(C26h, No. 176), with t = 7.358(1) A and c = 13.780(2) A. The experimental density for two molecules in the unit cell is 2.399(5) Mg m−3 (calculated, 2.402 Mg m−3). The single-crystal X-ray diffraction data refined by a full-matrix least-squares method have yielded R1 = 0.0160 and R2 = 0.0165, based on 858 unique reflections. The octahedral FeC6 groups are linked to the nine-coordinated NdN6(H2O)3 groups via cyanide bridging. The uncoordinated water molecule and the potassium ion occupy holes in the structure along a threefold axis above and below the Nd ion. Important bond lengths are: NdN = 2.518(3); FeC = 1.903(3); NdO = 2.685(3); and C = 1.166(4) A.

X-ray diffraction investigations and spectral analyses of monoclinic SmKFe(CN)6•3H2O

Abstract Single-crystal and powder X-ray diffraction data, X-ray fluorescence and thermal gravimetric analyses, conoscopic results, and infrared spectral data are presented for SmKFe(CN) 6 · 3H 2 O. The compound crystallizes in the monoclinic space group P2 1 m (No. 11), a = 7.329(2), b = 13.689(4), c = 7.324(3) A, β = 119.97(3)°, Z = 2, D m = 2.37(1) Mg m −3 , and D x = 2.376 Mg m −3 . Final least-squares full-matrix refinement yielded R = 0.0574 and R w = 0.0568 for 2138 unique reflections. The samarium ion is nine-coordinated forming a tricapped trigonal prism geometry. The octahedral FeC 6 groups are linked to the SmN 6 (H 2 O) 3 groups by cyanide bridging. The coordinated water molecules occupy general positions at two-thirds occupancy. The uncoordinated water molecule and the potassium ion (each at 0.5 occupancy) occupy holes in the structure. Important mean bond distances are: SmN = 2.478(5); SmO = 2.678(4); FeC = 1.899(5); and CN = 1.156(3) A.

A structural investigation of monoclinic SmCo(CN)6 · 4H2O

Abstract The crystal structure of SmCo(CN) 6 · 4H 2 O has been determined from three-dimensional, single-crystal, X-ray diffraction data and refined by the full-matrix least-squares method to give R = 0.0137 (R w = 0.0137) and ∑ 2 = 1.04. The compound crystallizes in the monoclinic space group P2 1 /m, a = 7.365(1), b = 13.653(2), c = 7.385(2) A˚, and β = 120.08(2)°. For Z = 2 , the calculated density is 2.261 Mg m −3 ( D m = 2.24(2)Mg m −3 ). A total of 882 unique reflections were measured with MoKα radiation by the ω-2θ scan technique. The Sm ion is eight-coordinated in a square antiprism geometry, the SmN 6 (H 2 O) 2 group. The Co ion is octahedrally coordinated to six carbon atoms, the CoC 6 group. These groups are connected by cyanide bridges. Two uncoordinated water molecules occupy holes in the structure. Important mean bond distances are: Sm N = 2.512, Sm O = 2.404, Co C = 1.890, and C N = 1.146A˚. Dehydration, fluorescence, and infrared data are reported.

Quasi-particle excitations and phonon broadening effects in the O ls spectra of Ln(OH)3 (Ln=La, Nd, Sm and Gd)

Abstract The O ls photoelectron spectra of Ln(OH)3 (Ln = La, Nd, Sm and Gd) can be approximated by the convolution of a core hole spectral density function and a response function which is related to the phonon broadening and instrumental broadening effects. A non-linear least-squares analysis on the convolution integral indicates that the lifetime of the O ls (in the energy domain) is strongly broadened by the phonon excitations. The FWHM (full width at half maximum) of the phonon excitations range from 1.3 to 2.6 eV.

Idealized eleven-coordinate geometries

Abstract The method of points on a sphere is employed to determine three types of eleven-coordinated polyhedra. These are: a pentacapped trigonal prism (D3h), a monocapped pentagonal antiprism (C5v), and a skewed trigonal prism with an interpenetrating pentagon (C2v). Associated relative repulsive energies for various particle potentials and polar coordinates are reported.