X-ray photoelectron spectroscopy: Towards reliable binding energy referencing

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

More than fifty years after the publication of the early work on conduction and dielectric breakdown of solids, we are still unable to describe quantitatively the electrical response of these materials. During this period of time, concepts derived from semiconductor physics have been transposed to the case of insulating solids, and among them, to polymers. Alternative descriptions have been proposed as well. In spite of this, there is still no agreement on how to describe charge transport and there is still some controversy as regards the applicability of semiconductors physics to the case of disordered insulating materials and in particular to polymers used in electrical engineering applications. The last twenty years have been marked by the publication of excellent review papers summarizing the physical concepts available to describe charge transport. Enormous steps forward have been achieved as regards computing facilities and our ability to spatially map the space charge, quantitatively, inside dielectric materials. We consider these two factors as fundamental in providing possibilities for developing sound models of charge transport, by using the basis of fundamental knowledge that has been accumulated in the previous years, and by coupling up-to-date techniques in experiments and in simulation. In this paper, which is not a review of either the published work on modeling or of new concepts in dielectric physics, we emphasize recent progress in the field of atomistic and macroscopic modeling and we discuss challenges based on such approaches that, we think, constitute a direction for future research.

Charge transport modeling in insulating polymers: from molecular to macroscopic scale

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

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

Molecular and solid water, a comparative esca study.

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

ICESS-9 - Proceedings of the Ninth International Conference on Electronic Spectroscopy and Structure - Uppsala, Sweden, June 30-July 4, 2003 - Foreword

J.J. Pireaux

Papers

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

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

Molecular and solid water, a comparative esca study.

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

ICESS-9 - Proceedings of the Ninth International Conference on Electronic Spectroscopy and Structure - Uppsala, Sweden, June 30-July 4, 2003 - Foreword