VISUALIZING ELECTRONIC ORBITALS. The image of an atom is really the image of its outermost electrons or, to be more precise still, the image of the averaged likelihood that the electrons will be at various places. For any but the innermost electrons, the shape of this likelihood surface (or orbital) will be non-spherical in shape. Physicists at Arizona State have now actually imaged these orbitals for the first time and shown that they look just the drawings used in quantum textbooks for decades. Using a combination of x-ray diffraction and electron microscopy the ASU scientists produced a 3D map of the orbitals of copper atoms and their bonds with neighboring atoms in a cuprite (Cu₂O) compound (see figure at Physics News Graphics). The images of Cu-O and Cu-Cu bonds might provide insight into the workings of high temperature superconductors, in which the whereabouts of electrons and holes (the voids left by vacated electrons) are crucial. (J.M. Zuo et al., Nature, 2 Sept. 1999.)