X-ray photoelectron spectroscopic and atomic force microscopic studies of pyrolytically coated graphite and highly oriented pyrolytic graphite used for electrothermal vaporization

Abstract

The interaction between solid or liquid samples on the one hand and pyrolytically coated graphite or highly oriented pyrolytic graphite (HOPG) sample holders on the other hand during electrothermal vaporization was studied. For the characterisation of the micrometer scale topographical changes occurring on these graphite surfaces as a result of solid sample evaporation, atomic force microscopy (AFM) was used. The migration of Cd(NO3)2 and Na2HAsO4 deposited as solutions on the surface of the HOPG was studied by depth resolved X-ray photoelectron spectroscopy (XPS) using argon ion sputter etching. It was found that the investigated compounds migrate into the graphite to a depth of at least 1-1.5 μm. XPS data suggest that the migration involves either the hydrated metal ions or the molecules.