(PF members Salman2 and ftr have already mentioned this in two threads, but I think it deserves it's own thread ) Hydrogen Atoms under Magnification: Direct Observation of the Nodal Structure of Stark States Abstract: To describe the microscopic properties of matter, quantum mechanics uses wave functions, whose structure and time dependence is governed by the Schrödinger equation. In atoms the charge distributions described by the wave function are rarely observed. The hydrogen atom is unique, since it only has one electron and, in a dc electric field, the Stark Hamiltonian is exactly separable in terms of parabolic coordinates (η, ξ, φ). As a result, the microscopic wave function along the ξ coordinate that exists in the vicinity of the atom, and the projection of the continuum wave function measured at a macroscopic distance, share the same nodal structure. In this Letter, we report photoionization microscopy experiments where this nodal structure is directly observed. The experiments provide a validation of theoretical predictions that have been made over the last three decades. Paper: http://prl.aps.org/abstract/PRL/v110/i21/e213001 Articles: 'Quantum microscope' peers into the hydrogen atom Viewpoint: A New Look at the Hydrogen Wave Function The First Image Ever of a Hydrogen Atom's Orbital Structure(*) Impressive technique and a beautiful experiment . (*) Bonus material (from 2009): I also recall this article, "Electron clouds: seeing is believing" from 2009, regarding this paper: Imaging the atomic orbitals of carbon atomic chains with field-emission electron microscopy.