Charge compensation and binding energy referencing in XPS analysis

Throughout the evolution of XPS, the ability to compensate for surface charging and accurately calibrate the binding energy scale, particularly with electrically inhomogeneous samples, has remained one of the most intractable problems. The last decade, however, has seen some quite significant advances in this area. Best exemplified perhaps by the Kratos (UK) 'in the lens' electrostatic mirror/electron source coupled with a magnetic immersion lens, a number of concepts have been advanced that take a quite different conceptual approach to charge compensation. They differ in a number of fundamental ways from the electron flood-type compensators, which are widely used and historically are absolutely essential with instruments based on monochromatized sources. Even more recent has been the use of combined ion and electron flood systems. Thus, modern approaches to compensation represent a more sophisticated understanding both of how charging arises and how it may be mitigated to improve the accuracy and utility of XPS spectra. Copyright © 1999 John Wiley & Sons, Ltd.