title: Low energy ion scattering: Determining overlayer thickness for functionalized gold nanoparticles.
abstract: With the widespread use of engineered nanoparticles for biomedical applications, detailed surface characterization is essential for ensuring reproducibility and the quality/suitability of the surface chemistry to the task at hand. One important surface property to be quantified is the overlayer thickness of self-assembled monolayer (SAM) functionalized nanoparticles, as this information provides insight into SAM ordering and assembly. We demonstrate the application of high sensitivity low energy ion scattering (HS-LEIS) as a new analytical method for the fast thickness characterization of SAM functionalized gold nanoparticles (AuNPs). HS-LEIS demonstrates that a complete SAM is formed on 16-mercaptohexadecanoic acid (C16COOH) functionalized 14 nm AuNPs. HS-LEIS also experimentally provides SAM thickness values that are in good agreement with previously reported results from simulated electron spectra for surface analysis (SESSA) analysis of X-ray photoelectron spectroscopy (XPS) data. These results indicate HS-LEIS is a valuable surface analytical method for the characterization of SAM functionalized nanomaterials.
authors.affiliation: National ESCA and Surface Analysis Center for Biomedical Problems, Departments of Bioengineering and Chemical Engineering, University of Washington, Seattle, WA, 98195.
authors.forename: Ali
authors.initials: A
authors.lastname: Rafati
authors.forename: Rik
authors.initials: R
authors.lastname: Ter Veen
authors.forename: David G
authors.initials: DG
authors.lastname: Castner
keywords: Gold nanoparticles; HS-LEIS; SESSA; XPS; characterization; overlayer thickness