  The force exerted on nanoparticles and atomic clusters by fast passing
electrons like those employed in transmission electron microscopes are
calculated and integrated over time to yield the momentum transferred from the
electrons to the particles. Numerical results are offered for metallic and
dielectric particles of different sizes (0-500 nm in diameter) as well as for
carbon nanoclusters. Results for both linear and angular momentum transfers are
presented. For the electron beam currents commonly employed in electron
microscopes, the time-averaged forces are shown to be comparable in magnitude
to laser-induced forces in optical tweezers. This opens up the possibility to
study optically-trapped particles inside transmission electron microscopes.
