X-ray photoelectron spectroscopy: Towards reliable binding energy referencing

The factors which influence chemical shifts are examined in order to elucidate the cause of the anomalous chemical shifts for Cd and Ag oxides. The effects of extra‐atomic relaxation are accounted for using a procedure employing experimental Auger and binding energies. Atomic partial ionic charges for some simple Cd, Ag, and Zn compounds are calculated from experimental binding energies using a model which includes the effects of lattice potentials and extra‐atomic relaxation. Inclusion of extra‐atomic relaxation effects did not have a drastic effect on the relative ionicities computed for these selected compounds. However, for CdO, a large extra‐atomic relaxation energy contribution reduces the binding energy by 0.5 eV more than is predicted from nearest neighbor electronegativity arguments.

Initial and final state effects in the ESCA spectra of cadmium and silver oxides

The C 1s signal from ubiquitous carbon contamination on samples forming during air exposure, so called adventitious carbon (AdC) layers, is the most common binding energy (BE) reference in X-ray photoelectron spectroscopy studies. We demonstrate here, by using a series of transition-metal nitride films with different AdC coverage, that the BE of the C 1s peak EBF varies by as much as 1.44 eV. This is a factor of 10 more than the typical resolvable difference between two chemical states of the same element, which makes BE referencing against the C 1s peak highly unreliable. Surprisingly, we find that C 1s shifts correlate to changes in sample work function ϕSA , such that the sum EBF+ϕSA is constant at 289.50±0.15 eV, irrespective of materials system and air exposure time, indicating vacuum level alignment. This discovery allows for significantly better accuracy of chemical state determination than offered by the conventional methods. Our findings are not specific to nitrides and likely apply to all systems in which charge transfer at the AdC/substrate interface is negligible.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/cphc.201700126

C 1s Peak of Adventitious Carbon Aligns to the Vacuum Level: Dire Consequences for Material's Bonding Assignment by Photoelectron Spectroscopy.

Correlation Effects in the Ionization of Molecules: Breakdown of the Molecular Orbital Picture

Core-electron binding energies for gaseous atoms and molecules

Core-electron relaxation energies and valence-band formation of linear alkanes studied in the gas phase by means of electron spectroscopy

Core and valence orbitals in solid and gaseous mercury by means of ESCA

A theoretical and experimental study of the carbon 1s shake-up structure of benzene

The valence electronic levels of the linear alkanes have been studied in the gas and solid phases by electron spectroscopy (AlK03B1) and ab initio calculations. With increasing size these quasi-linear molecules show the formation of a band structure. It appears that n-tridecane provides a convenient finite model for simulating the band structure of an infinite solid. The influence of aggre-

Étude de la structure électronique des hydrocarbures linéaires saturés en fonction de leur taille. - I. Evolution d'un niveau électronique vers une structure de bande

The core electron binding energies of the alkanes have been measured in the gas and solid phases by high resolution electron spectroscopy (AlK03B1). They slowly decrease over a range of 0.6 eV with the increasing size of the molecules in the gas phase. This small chemical shift is explained, with the aid of various theoretical models (CNDO/2 and 0394SCF ab initio), as being a consequence of the relaxation energy variations of the electronic shells during the photoemission. In the solid phase, the magnitude of the polarization or extramolecular relaxation energy amounts to about 10 % of the intramolecular relaxation energy. LE JOURNAL DE PHYSIQUE TOME 38, OCTOBRE 1977,

Étude de la structure électronique des hydrocarbures linéaires saturés en fonction de leur taille. - II. Mécanisme de relaxation électronique durant la photoémission

P.-A. Malmqvist

Papers

Core-electron relaxation energies and valence-band formation of linear alkanes studied in the gas phase by means of electron spectroscopy

Core and valence orbitals in solid and gaseous mercury by means of ESCA

A theoretical and experimental study of the carbon 1s shake-up structure of benzene

Étude de la structure électronique des hydrocarbures linéaires saturés en fonction de leur taille. - I. Evolution d'un niveau électronique vers une structure de bande

Étude de la structure électronique des hydrocarbures linéaires saturés en fonction de leur taille. - II. Mécanisme de relaxation électronique durant la photoémission