Significance and Use
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 non-conducting systems of the same element. It is assumed that the spectrometer is generally working properly for non-insulating specimens (see Practice E 902).
Although highly reliable methods have now been developed to stabilize surface potentials during XPS analysis of most materials (5, 6), no single method has been developed to deal with surface charging in all circumstances (10, 11). 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 acquaints the X-ray photoelectron spectroscopy (XPS) user with the various charge control and charge shift referencing techniques that are and have been used in the acquisition and interpretation of XPS data from surfaces of insulating specimens and provides information needed for reporting the methods used to customers or in the literature.
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 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, 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.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
E673 Terminology Relating to Surface Analysis
E902 Practice for Checking the Operating Characteristics of X-Ray Photoelectron Spectrometers
E1078 Guide for Specimen Preparation and Mounting in Surface Analysis
E1829 Guide for Handling Specimens Prior to Surface Analysis
charge control; charge referencing; charging; X-ray photoelectron spectroscopy; Surface analysis--spectrochemical analysis; Auger electron spectroscopy (AES); Bias referencing; Charge control/referencing; Gold decoration; Gold metals/alloys; Inert gases; Internal referencing; Key referencing; Surface charging; X-ray photoelectron spectroscopy (XPS);
ICS Number Code 71.040.50 (Physicochemical methods of analysis)
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Citing ASTM Standards
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