DEPTH SELECTIVE CEMS IN THE ENERGY-RANGE 0-KEV TO 20-KEV

The ''depth selectivity'' can be expressed by weight functions T(E,THETA)(x) giving the probability that electrons, starting in depth x, reach and leave the surface with an energy E, and an emission angle THETA relative to the surface normal. T(E,THETA)(x) was available up to now only for K conversion electrons of iron in the energy range 6.3-7.3 keV. To extend the available depth range for Fe-57 DCEMS, we calculated T(E,THETA)(x) for energies down to about 2 keV, and up to 14.4 keV, including K, L and M conversion and KLL Auger electrons. Based on these results a program has been developed to simulate for a given sample composition DCEMS and also ICEMS spectra. First results of electron transport calculations for the 19.6 keV L conversion electrons of Sn-119 indicate a reduced surface sensitivity in comparison to Fe-57, but the depth resolution seems to be reasonably good for deep layers.