X-ray photoelectron studies on some oxides and hydroxides of cobalt, nickel, and copper

Publisher Summary This chapter discusses statistical exchange-correlation in the self-consistent field. There are two sides to a self-consistent field calculation: the determination of the potential and the solution of Schrodinger's equation for the one-electron problem. The solution of Schrodinger's equation has fortunately advanced far enough through the application of the electronic digital computer so that it can be regarded for most purposes as being a standardized technique. The main point of the method of Gaspar, Kohn, and Sham is that they derive the approximate exchange correction from an approximate Hamiltonian for the system by varying the spin-orbitals to minimize the average value of this Hamiltonian for the ground state. The approximate Hamiltonian has many important and valuable features that are described in the chapter.

Statistical Exchange-Correlation in the Self-Consistent Field

This compilation revises the 1991 listing of atomic data for the lighter elements from hydrogen to gallium. The tabulation emphasizes resonance lines, i.e., lines whose lower level is the ground state, or an excited fine-structure state of the ground term, and is restricted to wavelengths longward of the H I Lyman limit at 911.753 ?. All but the very weakest known and predicted electric-dipole transitions are included, but no forbidden lines. This paper has attempted to review all data published by the end of 2002.?????The tables contain the best data available to the author on ionization potentials, level designations, vacuum and air wavelengths, lower and upper energy levels, statistical weights, transition probabilities, natural damping constants (reciprocal lifetimes), oscillator strengths, and the often used combinations of log gf and log ?f. All ion stages with relevant classified lines are included. Individual components resulting from isotope shift and hyperfine structure are listed explicitly for certain species. The accompanying text provides references, explanations for the critical selection of data, and notes indicating where new measurements or calculations are needed.?????This compilation should be particularly useful in the analysis of interstellar and quasar absorption lines and other astrophysical sites where the density of particles and radiation is low enough to excite only the lowest atomic levels. The data also are relevant to the study of stellar atmospheres, and gaseous nebulae.?????An Appendix summarizes new data relevant to the similar compilation in Paper II for the elements germanium to uranium.

https://iopscience.iop.org/article/10.1086/377639/pdf

Atomic Data for Resonance Absorption Lines. III. Wavelengths Longward of the Lyman Limit for the Elements Hydrogen to Gallium

Iron-based Fischer–Tropsch catalysts, which are applied in the conversion of CO and H2 into longer hydrocarbon chains, are historically amongst the most intensively studied systems in heterogeneous catalysis. Despite this, fundamental understanding of the complex and dynamic chemistry of the iron–carbon–oxygen system and its implications for the rapid deactivation of the iron-based catalysts is still a developing field. Fischer–Tropsch catalysis is characterized by its multidisciplinary nature and therefore deals with a wide variety of fundamental chemical and physical problems. This critical review will summarize the current state of knowledge of the underlying mechanisms for the activation and eventual deactivation of iron-based Fischer–Tropsch catalysts and suggest systematic approaches for relating chemical identity to performance in next generation iron-based catalyst systems (210 references).

The renaissance of iron-based Fischer-Tropsch synthesis: on the multifaceted catalyst deactivation behaviour.

Core-level binding-energy shifts at surfaces and in solids

X-ray study of inner level shifts and band structure of TiC and related compounds

The K?1?' structure is investigated experimentally for all pure elements of the first transition series and for some of their compounds. Analogous structures are found for L emission spectra of some second transition series elements as well as of some lanthanides. Relative transition energies and probabilities are calculated in a frozen-orbital approximation for the transition from a normal K state to singly ionized states of the configuration 3p53dn4s2 for the elements Sc-Ni. The results support the interpretation that the K?1?' structure is due to the electron interaction between partially filled 3p and 3d subshells. The electron interaction mechanism also explains the effects in the heavier elements investigated.

Electron Interaction in Transition Metal X-ray Emission Spectra

X-ray emission spectra of VCx, NbCx, TaCx, and ZrC

Radiative lifetimes of 8 different multiplets in the visible range in neutral sulphur have been directly measured using the High Frequency Deflection technique. These lifetimes have not been experimentally studied earlier. The results are compared to Coulomb approximation calculations and semiempirical estimates of the associated oscillator strengths.

Lifetimes of transitions in the visible range in neutral sulphur

Using a bent crystal spectrometer the Al Kα1,2 and α3 lines recorded in the first order of reflexion from quartz have been directly compared with the Cu Kα1 line recorded in the fifth order. The wavelength values of the Al K lines in A units, determined by Edlen and Svensson from Tyren's experimental work, have been used to calculate the conversion constants Λ and Λ*. The weighted mean value of Λ is found to be 1.002047 ± 0.000022 mA/XU and of Λ* 0.999972 ± 0.000022 A/A*.

Elisabeth Källne

Papers

X-ray study of inner level shifts and band structure of TiC and related compounds

Electron Interaction in Transition Metal X-ray Emission Spectra

X-ray emission spectra of VCx, NbCx, TaCx, and ZrC

Lifetimes of transitions in the visible range in neutral sulphur

Determination of the Conversion Constant Λ from the Al Kα Lines