We have investigated the changes produced in single-element and
two-layer transmission electron microscope (TEM) specimens irradiated by
an intense nanometer-sized electron probe, such as that produced in a
field-emission or aberration-corrected TEM. These changes include hole
formation and the accumulation of material within the irradiated area. The
results are discussed in terms of mechanisms, including electron-beam
sputtering and surface diffusion. Strategies for minimizing the effect of
the beam are considered.