DIRECT IMAGING OF EXCITED ELECTRONIC STATES USING DIFFRACTION TECHNIQUES - THEORETICAL CONSIDERATIONS

We illustrate that the change in electron density distribution upon el ectronic excitation of atoms can significantly change their X-ray and electron diffraction, suggesting that electronic structures of excited electronic states may be directly observed using optical pump-diffrac tion probe techniques, Three electronic states of lithium are used to demonstrate changes in X-ray and electron diffraction patterns. Even t hough the changes in the total electron densities are small, significa nt changes are observed in inverse k space, the domain of diffraction experiments. The pump-probe diffraction patterns are interpreted in te rms of extended and non-spherical structures of excited electronic sta tes.