At an earlier meeting [1], we discussed information retrieval in the
scanning transmission ion microscope (STIM) compared with the electron
microscope at the same energy. We treated elastic scattering contrast, using
total elastic cross sections; relative damage was estimated from energy loss
data. This treatment is valid for “thin” specimens, where the incident
particles suffer only single scattering. Since proton cross sections exceed
electron cross sections, a given specimen (e.g., 1
μg/cm2 of carbon at 25 keV) may be thin for
electrons but “thick” for protons. Therefore, we now extend our previous
analysis to include multiple scattering. Our proton results are based on the
calculations of Sigmund and Winterbon [2], for 25 keV protons on carbon,
using a Thomas-Fermi screened potential with a screening length of 0.0226
nm. The electron results are from Crewe and Groves [3] at 30 keV.
Interchain Spacing and Screening Length Modification of PSS Backbone Chains in Zwitterion-Doped Poly(3,4-Ethylenedioxythiophene):Polystyrene Sulfonate
