The ESCALAB 250Xi combines the following capabilities: Ultra-violet photoemission spectroscopy (UPS, with Helium excitation source, energy resolution 100 meV) to examine the density of occupied states of a given material. X-ray photoemission spectroscopy (XPS) to probe the core levels of the sampled material by collecting the photoelectrons emittedduring X-ray illumination (with double-focusing full 180° spherical sector analyzer, monochromatic Al KαX-ray source, energy resolution <0.45 eV). Angle-resolved XPS as a non-destructive technique that allows us to depth-profile the top ~5 nm of the sample. Angle-resolved UV photoemission spectroscopy (ARUPS) that enables probing the density of single-particle electronic excitations in the reciprocal space. XPS depth profiling (XPSDP), which combines a sequence of ion gun etch (monoatomic or polyatomic) cycles interleaved with XPS measurements from the current surface; and XPS imagining with a spatial resolution of ~3 μm.