[Perspective] Electron diffraction and the hydrogen atom

The humble hydrogen atom, with just a single proton and a single electron, is the key to many chemical and biological processes, but precisely because of its low number of electrons, it is difficult to detect even in a single-crystal x-ray diffraction (XRD) experiment. If the material is polycrystalline (crystal volume <100 µm3) and only powder-diffraction techniques can be applied, detection becomes almost hopeless unless sophisticated neutron-diffraction experiments are performed on c