Electrons frozen in motion

摘要

A single electron cloud in molecular nitrogen has been photographed. The snapshot is recorded so rapidly that it might become possible to image electron clouds as they change during fundamental molecular processes. In medical tomography, the three-dimensional shape of a person's innards is derived from a series of two-dimensional X-ray images recorded at different angles. On page 867 of this issue, Itatani et al. show how a new version of tomography, using laser pulses instead of X-ray beams, can determine the three-dimensional structure of a much smaller object: one of the electron clouds, or orbitals, in a nitrogen molecule (N_2).