Detecting Electron Motion in Atoms and Molecules

The detection of spatial and temporal electronic motion by scattering of subfemtosecond pulses of 10 keV electrons from coherent superpositions of electronic states of both H and T-2(+) is investigated. For the H atom, we predict changes in the diffraction images that reflect the time-dependent effective radius of the electronic charge density. For an aligned T-2(+) molecule, the diffraction image changes reflect the time-dependent localization or delocalization of the electronic charge density.