ASTM E1523-03

The acquisition of chemical information from variations in the energy position of peaks in the XPS spectrum is of primary interest in the use of XPS as a surface analytical tool. Surface charging acts to shift spectral peaks independent of their chemical relationship to other elements on the same surface. The desire to eliminate the influence of surface charging on the peak positions and peak shapes has resulted in the development of several empirical methods designed to assist in the interpretation of the XPS peak positions, determine surface chemistry, and allow comparison of spectra of conducting and nonconducting systems of the same element. It is assumed that the spectrometer is generally working properly for non-insulating specimens (see Practice E 902).

No ideal method has been developed to deal with surface charging (3, 4). For insulators, an appropriate choice of any control or referencing system will depend on the nature of the specimen, the instruments, and the information needed. The appropriate use of charge control and referencing techniques will result in more consistent, reproducible data. Researchers are strongly urged to report both the control and referencing techniques that have been used, the specific peaks and binding energies used as standards (if any), and the criteria applied in determining optimum results so that the appropriate comparisons may be made.

1.1 This guide covers the acquainting of the XPS user with the various charge control and charge shift referencing techniques that are and have been used in the acquisition and interpretation of X-ray photoelectron spectroscopy (XPS) data from surfaces of insulating specimens.

1.2 This guide is intended to apply to charge control and charge referencing techniques in XPS and is not necessarily applicable to electron-excited systems.

1.3 SI units are standard unless otherwise noted.

1.4 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.