The picture depicts a single hydrogen atom being removed from a surface, using a beam of electrons from an atomically sharp tip.
The green image shows a scanning tunnelling micrograph of a 10 nanometre wide area of a titanium dioxide surface. The microscope uses the tip, represented by a pyramid of spheres in this picture, to trace the surface on the atomic-scale, outputting a vastly magnified contour map. The alternating ridges and grooves in the image correspond to rows of titanium and oxygen, respectively. The white dimples, which straddle the grooves, result from hydrogen atoms attached to the oxygen rows. There are no hydrogen atoms on the right-hand side of the surface because they have already been removed, atom-by-atom, via these electron beams from the tip.
The green image shows a scanning tunnelling micrograph of a 10 nanometre wide area of a titanium dioxide surface. The microscope uses the tip, represented by a pyramid of spheres in this picture, to trace the surface on the atomic-scale, outputting a vastly magnified contour map. The alternating ridges and grooves in the image correspond to rows of titanium and oxygen, respectively. The white dimples, which straddle the grooves, result from hydrogen atoms attached to the oxygen rows. There are no hydrogen atoms on the right-hand side of the surface because they have already been removed, atom-by-atom, via these electron beams from the tip.