Hot-electron diffusion lengths in the rare-gas solids

Measurements of the secondary-electron escape probability have been used to determine the escape depth of hot electrons in thin films of Ne, Ar, and Xe. The electrons were generated with 5.9-keV x rays, and the data were analyzed using a diffusion model including absorption at the substrate. The escape depths are measured to be 0.23, 0.45, and 25 {μ}m for Xe, Ar, and Ne, respectively, and appear to be limited by trapping at defects. It is demonstrated that the long escape depths make the rare-gas solids efficient photocathodes for x rays.