Photoelectron determination of mean free paths of 200-1500-eV electrons in potassium iodide

The total inelastic mean free path in polycrystalline KI for electrons of energy 200-1500 eV has been measured to an accuracy of approximately ±12% by a photoelectron overlayer technique. Values range from 28 Å at 192 eV to 70 Å at 1404 eV. A theoretical model, based on a semiempirical tight-binding approximation, modified to take account of the attractive and repulsive effects of the ${\mathrm{K}}^{+}$ and ${\mathrm{I}}^{-}$ ions on the incident electrons, has been used to calculate such mean free paths in KI. The agreement of these calculations with the experimental results is good.