Paper AS+MI+SS-TuM1
Effective Attenuation Lengths for Different Quantitative Applications of XPS

Tuesday, October 31, 2017, 8:00 am, Room 13

The effective attenuation length (EAL) is a convenient parameter for use in place of the inelastic mean free path (IMFP) to account for elastic scattering of signal photoelectrons in XPS. The most common EAL application is measuring the thicknesses of overlayer films on planar substrate from the attenuation of substrate photoelectrons in laboratory XPS systems. EALs for this purpose can be obtained from a NIST database [1] and from empirical predictive equations [2]. In addition, EALs can be defined for other quantitative applications of XPS with laboratory XPS systems: (i) determination of thicknesses of overlayer films on planar substrates from changes of intensities of overlayer photoelectrons [3]; (ii) quantitative determination of surface composition by XPS [4]; and (iii) determination of shell thicknesses of core-shell nanoparticles [5]. Finally, EALs have been determined for measuring thicknesses of overlayer films on planar substrate from the attenuation of substrate photoelectrons in XPS with linearly polarized X-rays with energies up to 10 keV [6]. These EALs will be compared to corresponding EALs for unpolarized X-rays [2,6]. The EAL is not a simple material parameter like the IMFP but depends on the defining equation for the particular application as well as on the experimental configuration.

1. NIST Electron Effective-Attenuation-Length Database, SRD 82, Version 1.3, 2011; https://www.nist.gov/srd/nist-standard-reference-database-82.

2. A. Jablonski and C. J. Powell, J. Electron Spectrosc. Relat. Phenom. 199, 27 (2015).

3. A. Jablonski, J. Electron Spectrosc. Relat. Phenom. 185, 498 (2012).

4. A. Jablonski and C. J. Powell (to be published).

5. C. J. Powell, W. S. M. Werner, A. G. Shard, and D. G. Castner, J. Phys. Chem. C 120, 22730 (2016).

6. A. Jablonski (to be published).