title: Cryo ultra-low-angle microtomy for XPS-depth profiling of organic coatings.
abstract: In X-ray photoelectron spectroscopy (XPS) Ar(+) ion sputtering is usually used for depth profiling. However, for such samples as organic coatings, this is not feasible because of degradation. Also, measurement of a depth profile on a conventionally prepared cross-section is not possible if, for example, sample thickness is below the smallest available measurement spot size of the XPS system. In our approach we used a rotary microtome to cut samples under a shallow tilting angle of 0.5° to obtain an extended cross-section suitable for XPS investigations. We also used liquid nitrogen cooling to ensure an exposed area of higher quality: topography measurements with a novel optical 3D microscope and by atomic force microscopy revealed the linearity of the inclined sections. With our cryo ultra-low-angle microtomy (cryo-ULAM) preparation technique we were able to determine, by XPS, elemental and chemical gradients within a 25 μm thick polyester-based organic coating deposited on steel. The gradients were related to, for example, depletion of the crosslinking agent in the sub-surface region. Complementary reflection electron energy-loss spectroscopy measurements performed on the cryo-ULAM sections also support the findings obtained from the XPS depth profiles.
authors.affiliation: Christian Doppler Laboratory for Microscopic and Spectroscopic Material Characterisation, Center for Surface and Nanoanalytics, Johannes Kepler Universität Linz, Altenbergerstraße 69, 4040 Linz, Austria. theresia.greunz@jku.at
authors.forename: T
authors.initials: T
authors.lastname: Greunz
authors.forename: B
authors.initials: B
authors.lastname: Strauß
authors.forename: S E
authors.initials: SE
authors.lastname: Schausberger
authors.forename: B
authors.initials: B
authors.lastname: Heise
authors.forename: B
authors.initials: B
authors.lastname: Jachs
authors.forename: D
authors.initials: D
authors.lastname: Stifter