National Synchrotron Light Source Seminar

The talk is devoted to the use of scanning photoemission microscopies in material studies. The surface, electronic, chemical and structural sensitivity of photoemission makes it an instrument that is very useful for material studies like strongly electronically correlated systems, catalysts, superconductors, graphene, etc.
With the photon spot of small size (less than 1 m) photoemission acquires spatial resolution, substantially extending research possibilities. For example, extremely small samples could be studied, like graphene flakes, polycrystalline domains, single crystals that couldn’t be grown to large sizes, etc. Another interesting possibility are the systems with intrinsic spatial inhomogeneties in electronic and/or chemical properties. The good examples are the domains in conductivity formed under the conditions of the metal to insulator transition. Further, the artificial structures with micron sizes could be studied.
At Elettra the core level and VB/ARPES photoemission microscopies are developed at the beamlines of ESCA microscopy and Spectromicroscopy, respectively. The former is well known to provide mapping of surfaces with spatial resolution of 200 nm and highly relevant chemically, due to high sensitivity of core level lineshape to local environment of the atom. The beamline successfully used in studies of OLED, fuel cells, catalysts, nanotubes, semiconducting heterostructures, etc.
The upgrade of SpectroMicroscopy beamline dedicated to the development of spatially resolved ARPES has been commissioned few years ago. Now it builds up the user community by offering the possibility of ARPES with spatial resolution less than 1 micron. Up to now, the spatially resolved ARPES has been already used in studies of various materials with strong electronic correlations: superconductors, graphene, CDW materials (TaS2 and TaSe2), vanadium oxides, etc. The correlated use of shallow core level (less than 70 eV in binding energy) and ARPES microsc