Nanometre-scale electron-beam drilling was carried out on vacuum-deposited monocrystalline films, in a 200kV high-resolution transmission electron microscope, using a thermionic gun. It was found that holes formed due to a surface mass-loss mechanism. Surface atomic diffusion and desorption were observed  in situ  at a spatial resolution of 0.2nm and a time resolution of 1/60s. It was found that most of the surface atoms first began to diffuse around steps on the surface, under the electron irradiation, and then desorbed into the vacuum at weakly-bonded positions such as steps, kinks and isolated positions on the surface.

T.Kizuka, N.Tanaka: Philosophical Magazine Letters, 1997, 76[4], 289-97