The 4f shell filling begins with Ce and ends with Yb, both elements appearing with or without magnetic moment depending on chemical environment. This magnetic ambivalence is reflected in unusual physical properties in numerous Ce and Yb intermetallics, the subject of this talk.

Surface Science evolved from the need to understand interfaces in semiconductor manufacturing and heterogeneous catalysis, and relied heavily on model surfaces mimicking specific aspects of the more complex "real" surfaces of technological relevance. Most methods to characterize the structure and composition of surfaces with atomic precision traditionally required a vacuum environment, if not for the probes used (electrons, ions, atoms...), then to avoid contamination of the surfaces from an ambient atmosphere.