SPELEEM: Combining LEEM and spectroscopic imaging

At present the only surface electron microscope which allows true character istic XPEEM (photoemission electron microscopy using synchrotron radiation) and structural characterization is the spectroscopic LEEM developed at the Technical University Clausthal in the early nineties. This instrument has in the past been used mainly for LEEM studies of various surface and thin f ilm phenomena, because it had very limited access to synchrotron radiation. Now the microscope is connected quasipermanently to the undulator beamline 6.2 at the storage ring ELETTRA, operating successfully since the end of 1 996 under the name SPELEEM (Spectroscopic PhotoEmission and Low Energy Elec tron Microscope). The high brightness of the ELETTRA light source, together with an optimized instrument, results in a spatial resolution better than 25 nm and an energy resolution better than 0.5 eV in the XPEEM mode. The in strument can be used alternately for XPEEM, LEEM, LEED (low energy electron diffraction), MEM (mirror electron microscopy) and other imaging modes, de pending upon the particular problem studied. The combination of these imagi ng modes allows a comprehensive characterization of the specimen. This is o f particular importance when the chemical identification of structural feat ures is necessary for the understanding of a surface or thin film process. In addition, PED (photoelectron diffraction) and VPEAD (valence photoelectr on angular distribution) of small selected areas give local atomic configur ation and band structure information, respectively.