C. Nordling

Molecular Spectroscopy by Means of ESCA II. Sulfur compounds. Correlation of electron binding energy with structure

Electron spectra from an extensive series of sulfur compounds have been studied. A correlation has been established between the observed position of inner electron lines of sulfur and structure. The influence of structure on the electron binding energies is discussed in terms of a calculated atomic charge, based on the concepts of electronegativity and partial ionic character of bonds. The results are useful for the study of bonding and structure in sulfur chemistry, and are applied particularly to the discussion of the sulfur-oxygen bond (S=O).

Charge transfer in transition metal carbides and related compounds studied by ESCA

Abstract Electron spectroscopic measurements of binding energy shifts of Cl s electrons in Group 4 b , 5 b and 6 b carbides and of core electrons in Ti and V compounds are presented. The results are discussed and compared with X-ray spectroscopic investigations and energy band calculations. It is shown that electrons are transferred from the metal to the carbon atoms when a carbide of this type is formed.

Molecular Spectroscopy by Means of ESCA III. Carbon compounds

Carbon 1s energies are measured by ESCA for a series of aliphatic saturated compounds, carbonyl compounds, and some aromatic compounds. For convenient use in chemical structure analysis the binding energy shifts are correlated with a charge parameter obtained from electronegativity considerations. The shifts are also analyzed in terms of group shifts from which group electronegativities are derived. A comparison is made between the shifts in solid and gaseous samples and it is shown that solid state effects are small for non-ionic compounds. The observed shifts are then compared with results of semi-empirical and ab initio molecular orbital calculations on free molecules. The theoretical calculations are simplified by use of an electrostatic potential model.

Band Structure of Transition Metals Studied by ESCA

The position and shape of the energy bands of the following transition metals have been studied by ESCA: Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Os, Ir, Pt, Au. The Fermi levels of the metals with unfilled d-bands are found in the high-energy flanks of the valence band spectra. For the noble metals the Fermi level is shifted toward higher energies. These observations are in general accordance with the overlap of d- and sp-bands in transition metals. An increase in band width is noted between corresponding elements in each series of transition metals. A comparison is drawn between band widths obtained in the present study and those deduced from cohesive energy data. An observed splitting in some of the bands seems to be much too large to be attributable to spin-orbit interaction. Core electron lines are recorded for the purpose of obtaining an energy calibration, estimating the contribution to the observed band spectra from inelastically scattered electrons, and checking the chemical state of the sample. The photoexcitation process and the energy losses of the electrons due to single-particle and plasmon excitations are discussed.

Valence Bands and Core Levels of the Isoelectronic Series LiF, BeO, BN, and Graphite Studied by ESCA

The core lines and valence bands of LiF, BeO, BN and graphite have been studied by the ESCA technique. The energy differences between inner levels and valence bands are compared with X-ray transition energies. The changes in binding energy for the Bels level when going from metal to oxide and fluoride are compared with X-ray spectroscopic data and with a study of the disintegration constant in electron capture of 7Be in the same compounds.

Escape Depths of X-ray Excited Electrons

The escape depth of X-ray induced photoelectrons and Auger electrons has been measured for energies between 1 keV and 4 keV in metallic gold and aluminum oxide. The escape depth was found to be proportional to the square root of the electron energy and ranged from 19 ? (at 0.9 keV) to 37 ? (at 3.2 keV) in gold and from 13 ? (at 1.4 keV) to 22 ? (at 3.9 keV) in aluminum oxide.

Electron escape depth in silicon

Abstract The ESCA electron escape depth in silicon is determined from the peak areas in the electron spectra from evaporated thin films. For electron energies in the region 320 eV to 3.6 keV values from 13 to 83 A are obtained. The escape depth in silicon dioxide is determined for the energies 1.6 and 3.6 keV. Binding energies and Auger energies are determined in silicon and silicon oxides.

Electron Spectroscopic Investigation of Auger Processes in Bromine Substituted Methanes and Some Hydrocarbons

Auger spectra in gaseous CH4, CH3Br, CH2Br2, CHBr3, CBr4, C2H6, and C6H6 are excited by electron impact at about 5 keV energy and observed by means of a spherical electrostatic spectrometer at 90° to the primary electron beam. Besides the energies and the intensities of the Auger lines and the chemical shifts, the analysis of the spectra gives the energies and the lifetimes of the doubly ionized molecules. The line widths together with energy considerations indicate that some of these doubly ionized molecules rapidly dissociate. Comparisons are also made between the bromine and the carbon spectra.

Determination of the electron escape depth in gold by means of ESCA

Abstract The intensity of core electrons photoexcited by soft X-ray has been determined as a function of the thickness of deposited metal films. An escape depth of (22 ± 4) A is obtained for 1.2 keV electrons in gold. The possible impact of this result on band structure studies is discussed.

VC, NbC and TaC with varying carbon content studied by ESCA☆

Abstract Electron spectroscopic studies by the ESCA technique of core level electrons in VC, NbC and TaC with varying carbon contents show that the electron transfer from the metal atoms increases with increasing carbon content in the VC phase but decreases in the NbC and TaC phases. The VC phase resembles the TiC phase measured in a previous investigation. The ESCA shifts are compared with heats of formation.