Figure 4.

Simulation of pathways of electrons during (S)TEM imaging simulated with the CASINO software package. (A) Schematic of the simulated geometry. A 1 μm water layer was placed between 50 nm silicon nitride spacers. A silica sphere of 113 nm of diameter was placed on the top window. (B) Calculation of the energy deposited to the silica particle via elastic and inelastic interactions of the incident electrons (in keV) for a frame acquired with a (S)TEM operated at 200 keV with 1.58 nm pixel size, 10 pA of beam current and 16 μs dwell time. The pixel size of the energy distribution corresponds to the pixel size used during imaging. The energy values indicate the deposited energy on the silica sphere from the electrons initially incident on that pixel. (C) Absorbed energy per unit volume of a silica particle located at the top SiN window for a number of electron beam currents with the previous imaging conditions. (D) Absorbed energy per unit volume of a silica particle located at different depths from the top SiN window for the case of 1 pA beam current.