Metal surface at the quantum level. This depiction of a metal surface is obtained by applying the Helium-3 spin-echo technique. This technique requires firing a beam of polarised 3He atoms towards the surface of the metal so that the energy changes during scattering can be measured. Here, the metal can be seen as a lattice of positive metal ions (blue) in a sea of electrons (red). Th spin-echo technique can record measurements on the sub-nanometre and nanosecond scales, and the results built up digitally to reveal a three-dimensional image of the surface.