Hydrogen atoms in a crystal have been directly imaged using a state-of-the-art transmission electron microscope, reports a paper online this week in Nature Materials.

Developments in electron optics during the past few years have allowed the imaging of several light elements. Hydrogen — the lightest of all — has eluded even the most powerful microscopes because of its very weak interaction with electron beams. Eiji Abe and co-workers have now achieved the goal of imaging atoms of this element in a specimen of yttrium hydride (YH2). They use a particular configuration of scanning transmission electron microscopes named annular bright field, in which an electron beam hits a crystal on one side and the atoms appear as dark spots on the images detected on the other side.