title: XPS characterization of Au (Core)/SiO2 (shell) nanoparticles.
abstract: Core-shell nanoparticles with ca. 15-nm gold core and 6-nm silica shell were prepared and characterized by XPS. The Au/Si atomic ratio determined by XPS is independent of the electron takeoff angle because of the concentric spherical shape of the nanoparticles. The formula given by Wertheim and DiCenzo (Phys. Rev. B 1988, 37, 844) for spherical nanoparticles and the modified one by Yang et. al. (J. Appl. Phys. 2005, 97, 024303) for core-shell nanoparticles are used to correlate the XPS-derived composition with the geometry of the nanoparticles only after significantly modifying either the bulk density of the silica shell or the attenuation length of the photoelectrons.
authors.forename: Ilknur
authors.initials: I
authors.lastname: Tunc
authors.forename: Sefik
authors.initials: S
authors.lastname: Suzer
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Correa-Duarte
authors.forename: Luis M
authors.initials: LM
authors.lastname: Liz-Marzán