May 4, 2020
Journal Article

Versailles Project on Advanced Materials and Standards Interlaboratory Study on Measuring the Thickness and Chemistry of Nanoparticle Coatings Using XPS and LEIS

Yung-Chen Wang
Wolfgang Werner
Li Yang
A Shard
Natalie Belsey
David Cant
Caterina Minelli
Joyce Araujo
Bernd Bock
David Castner
Giacomo Ceccone
Jonathan Counsell
Paul Dietrich
Mark Engelhard
Sarah Fearn
Carlos Galhardo
Henryk Kalbe
Jeongkwon Kim
Luis Lartundo-Rojas
Henry Lufman
Tim Nunney
Johannes Pseiner
Emily Smith
Valentina Spampinato
Jacobus Sturm
Andrew Thomas
Jon Treacy
Lothar Veith
Mike Wagstaffe
Hai Wang
Meiling Wang
Philipp Brüner

Abstract

We report the results of a VAMAS (Versailles Project on Advanced Materials and Standards) inter-laboratory study on the measurement of the shell thickness and chemistry of nanoparticle coatings. Peptide-coated gold particles were supplied to laboratories in two forms: a colloidal suspension in pure water and; particles dried onto a silicon wafer. Participants prepared and analyzed these samples using either X-ray photoelectron spectroscopy (XPS) or low energy ion scattering (LEIS). Careful data analysis revealed some significant sources of discrepancy, particularly for XPS. Degradation during transportation, storage or sample preparation resulted in a variability in thickness of 53 %. The calculation method chosen by XPS participants contributed a variability of 67 %. However, variability of 12 % was achieved for the samples deposited using a single method and by choosing photoelectron peaks that were not adversely affected by instrumental transmission effects. The study identified a need for more consistency in instrumental transmission functions and relative sensitivity factors, since this contributed a variability of 33 %. The results from the LEIS participants were more consistent, with variability of less than 10 % in thickness and this is mostly due to a common method of data analysis. The calculation was performed using a model developed for uniform, flat films and some participants employed a correction factor to account for the sample geometry, which appears warranted based upon a simulation of LEIS data from one of the participants and comparison to the XPS results.

Revised: May 4, 2020 | Published: September 13, 2016

Citation

Belsey N.A., D. Cant, C. Minelli, J.R. Araujo, B. Bock, P. Brüner, and D.G. Castner, et al. 2016. "Versailles Project on Advanced Materials and Standards Interlaboratory Study on Measuring the Thickness and Chemistry of Nanoparticle Coatings Using XPS and LEIS." Journal of Physical Chemistry C 120, no. 42:24070-24079. PNNL-SA-121117. doi:10.1021/acs.jpcc.6b06713