Measurement of the Spectral Distribution of Low Energy Electrons Emitted as a Result of M$_{3}$VV Auger Transitions in Cu(100)*

Auger Photoelectron Coincidence Spectroscopy (APECS) was used to investigate the physics of the Low Energy Tail (LET) region of the Auger spectrum of a Cu(100) sample. A beam of 200eV photons was used to probe the sample. Two Cylindrical Mirror Analyzers (CMAs) were used to select the energy of electrons emitted from the sample. An APECS technique was used to obtain an Auger spectrum with one of the CMAs fixed at the core photoemission peak. The spectrum contains the extrinsic contributions from electrons excited by the M$_{3}$VV Auger transition plus a background due to true coincidence between photo-emitted valence band electrons that undergo inelastic~scattering and other valence electrons. To remove the extrinsic contribution to the LET of the Auger Spectrum, Coincidence measurements were made with the fixed analyzer set at various energies (150eV, 165eV, 180eV, 190eV and 197eV) between the core and the valence band and obtain an estimate of the background due to the inelastic scattering of the valence band electrons. The extrinsic contribution to the LET was then subtracted to get the final spectrum consisting of the secondary electrons that are intrinsic to the M$_{3}$VV Auger transition only.