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C.J. Powell, W.S.M. Werner, A. Shard, D. Castner:
"Evaluation of Two Methods for Determining Shell Thicknesses of Core-Shell Nanoparticles by X-ray Photoelectron Spectroscopy
";
Journal of Physical Chemistry C, 120 (2016), 22730 - 22738.

We evaluated two methods for determining shell thicknesses of core−shell
nanoparticles (NPs) by X-ray photoelectron spectroscopy. One of these methods had been
developed for determining thicknesses of films on a planar substrate while the other was developed
specifically for NPs. Our evaluations were based on simulated Cu 2p3/2 spectra from Cu-core/Cushell
NPs with a wide range of core diameters and shell thicknesses. Copper was chosen for our
tests because elastic-scattering effects for Cu 2p3/2 photoelectrons excited by Al Kα X-rays are
known to be strong. Elastic scattering could also be switched off in our simulations so that the two
methods could be evaluated in the limit of no elastic scattering. We found that the first method,
based on both core and shell photoelectron intensities, was unsatisfactory for all conditions. The
second method, based on an empirical equation for NPs developed by Shard, also utilized both core
and shell photoelectron intensities and was found to be satisfactory for all conditions. The average
deviation between shell thicknesses derived from the Shard equation and the true values was −4.1% when elastic scattering was
switched on and −2.2% when elastic scattering was switched off. If elastic scattering was switched on, the effective attenuation
length for a Cu film on a planar substrate was the appropriate length parameter while the inelastic mean free path was the
appropriate parameter when elastic scattering was switched off.