Ecole Polytechnique F¶ed¶erale de Lausanne,

High-resolution transmission electron microscopy shows that metal nanoparticles sin-ter within a fraction of a second under an electron beam at `room temperature ’ as long as classical models of thermal equilibrium apply. Images exhibit crystal planes that change in orientation with time as if the particle was undergoing melting and re-solidi cation processes. We explore whether these dynamical e¬ects are the result of heating or transformation e¬ects in the electron microscope or quantum ®uctuations in small systems