Photoelectron spectra of substituted benzenes

Photoelectron spectra of several substituted dimethylanilines, nitrobenzenes, acetophenones and nitrosobenzenes have been studied with a view to examine the electronic effects of substituents on the various φ and n levels. The results are discussed in the light of molecular orbital calculations and electronic absorption spectra. Correlation of substituent effects on the IE's with π-electron densities and Hammett substituent constants has enabled rationalization of all available data on mono- and disubstituted benzenes. The IE's generally increase with the electron-withdrawing power of the substituents.     

Investigation of the fermi edge in sodium tungsten bronzes by photoelectron spectroscopy

High-resolution photoelectron spectra of sodium tungsten bronzes Na _xWO₃ (0.26<x< 0.76) reveal a linear variation in the density of states at the Fermi energy as a function of sodium content. This behaviour does not appear to arise from filling of a rigid conduction band. Magnetic susceptibilities calculated from photoemission data using a simple independent-electron model agree with measured values.     

Stereochemistry of post-transition metal oxides: revision of the classical lone pair model

The chemistry of post transition metals is dominated by the group oxidation state N and a lower N-2 oxidation state, which is associated with occupation of a metal s(2) lone pair, as found in compounds of Tl(I), Pb(II) and Bi(III). The preference of these cations for non-centrosymmetric coordination environments has previously been rationalised in terms of direct hybridisation of metal s and p valence orbitals, thus lowering the internal electronic energy of the N-2 ion. This explanation in terms of an on-site second-order Jahn-Teller effect remains the contemporary textbook explanation. In this tutorial review, we review recent progress in this area, based on quantum chemical calculations and X-ray spectroscopic measurements. This recent work has led to a revised model, which highlights the important role of covalent interaction with oxygen in mediating lone pair formation for metal oxides. The role of the anion p atomic orbital in chemical bonding is key to explaining why chalcogenides display a weaker preference for structural distortions in comparison to oxides and halides. The underlying chemical interactions are responsible for the unique physicochemical properties of oxides containing lone pairs and, in particular, to their application as photocatalysts (BiVO(4)), ferroelectrics (PbTiO(3)), multi-ferroics (BiFeO(3)) and p-type semiconductors (SnO). The exploration of lone pair systems remains a viable a venue for the design of functional multi-component oxide compounds.     

Empty electronic states in the sodium tungsten bronzes: a study by inverse photoemission spectroscopy

Empty electronic states in the sodium tungsten bronze $\text{Na}{}_{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}\text{WO}{}_3$ have been studied by inverse photoemission spectroscopy using a novel narrow-bandpass photon detector. The empty density of states in the t_2g(W:5d) band peaks about 3 eV above the Fermi energy, implying an overall t_2g bandwidth greater than found in recent bandstructure calculations.     

RESTRICTED LIE ALGEBRAS WITH MAXIMAL 0-PIM

In this paper it is shown that the projective cover of the trivial irreducible module of a finite-dimensional solvable restricted Lie algebra is induced from the one dimensional trivial module of a maximal torus. As a consequence, the number of the isomorphism classes of irreducible modules with a fixed p-character for a finite-dimensional solvable restricted Lie algebra L is bounded above by p ^MT(L), where MT(L) denotes the maximal dimension of a torus in L. Finally, it is proved that in characteristic p > 3 the projective cover of the trivial irreducible L-module is induced from the one-dimensional trivial module of a torus of maximal dimension, only if L is solvable.     

Surface structure of In2O3(111) (1 × 1) determined by density functional theory calculations and low energy electron diffraction

The surface structure of In₂O₃(111) has been investigated by dynamical analysis of low energy electron diffraction data, in conjunction with first principles calculations using density functional theory. The experimental data set consisted of eight independent beams whose intensities were measured for incident energies in the range between 25 eV and 250 eV. In fitting the experimental data it was essential to treat the radii of In and O spheres as variable parameters: following this procedure a final Pendry R factor of 0.31 was obtained. The LEED results are compatible with the calculations and both analyses suggest that the surface structure involves only small vertical relaxations in the outermost of the {[O^2?]₁₂^24?[In³⁺]₁₆⁴⁸⁺[O^2?]₁₂^24?} quadrupolar units that define the (111) surface. The ab initio slab calculations also confirm that lateral relaxations not considered in fitting the experimental data are of very minor importance.