NEW HIGH-RESOLUTION ELECTROSTATIC ELECTRON SPECTROMETER FOR CONVERSION ELECTRON MOSSBAUER-SPECTROSCOPY

The construction and performance of a new electron spectrometer using an electrostatic 90 degrees-spherical deflection analyzer (SDA) is described. The spectrometer is suited for depth-selective conversion-electron Mossbauer spectroscopy (DCEMS) on surfaces and thin films in ultra-high vacuum (UHV) at temperatures ranging between 40-1000 K using K- and L-conversion electrons of Fe-57. The spectrometer is designed for 2% electron-energy resolution and about 5% (of 4 pi) transmission for 7.3 keV K-conversion electrons of Fe-57. The energy resolution has been confirmed experimentally. We demonstrate that DCEMS in general and our instrument in particular are capable of detecting a thin (similar to 50 Fe Angstrom) Mossbauer-inert buried oxide layer located at the surface of a stainless steel substrate and covered by an Fe/Cr bilayer.