| AVS 63rd International Symposium & Exhibition | |
| Applied Surface Science | Monday Sessions |
| Session AS-MoM |
| Session: | Quantitative Surface Analysis: New Ways to Perform Old Tricks |
| Presenter: | David Cant, National Physical Laboratory, UK |
| Authors: | D.J.H. Cant, National Physical Laboratory, UK Y.C. Wang, University of Washington D.G. Castner, University of Washington A.G. Shard, National Physical Laboratory, UK |
| Correspondent: | Click to Email |
There is currently great interest in the study of core-shell and core-multi-shell nanoparticles. XPS, as a highly surface sensitive and quantitative analysis method, is potentially of great use in the characterisation of these nanoparticle systems. In particular, understanding the chemical composition and thickness of nanoparticle shells is of great importance for understanding how a given nanoparticle system may interact with its environment. More complicated structures, such as core-shell-shell systems are now commonly studied, whether in the context of core-shell systems affected by adventitious carbon contamination or systems with a core-shell-shell structure by design, and as such there is a need for analysis methods capable of providing quantitative information on the structures of such systems.
Straightforward methods for the characterisation of planar overlayers via the use of XPS have been available for some time1, however such planar analysis techniques are clearly unsuited to providing reasonable estimates of nanoparticle shell thicknesses. Several methods exist for the quantitative analysis of shells in core-shell nanoparticle systems via XPS, including by comparison to simulated data2,3 or by direct calculation from empirical formulae4. While comparison to simulation can also be used to characterise core-shell-shell nanoparticles, such methods typically require specialist software or expertise, and are not necessarily easily applicable by the general practitioner of XPS. As such, it is important to consider whether a simpler technique for core-shell-shell systems, accessible to any analyst, can be conceived. While not as straightforward as for the core-shell case, an empirical formula for the calculation of core-shell-shell nanoparticle shell thicknesses has been developed5 as an extension to the TNP formula4 for core-shell nanoparticles. This technique requires no specialist knowledge or software, and with a few iterations converges rapidly upon estimates of shell thickness with a deviation typically lower than the error expected in the estimation of the required electron attenuation lengths.
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5. Cant, D. J. H., Wang, Y.-C., Castner, D. G. & Shard, A. G. -Surf. Interface Anal.48, 274–282 (2016).