Experimental charge densities in chemistry: what is next?

After extensive development of experimental and calculational methods and concepts, experimental charge densities from diffraction measurements are now being more widely applied to chemical and physical problems. Examples are the calculation of the Coulombic contribution to molecular interactions, the study of bonding-induced changes in transition-metal ligands, the establishment of the electronic ground state of transition-metal complexes, and the calibration of theoretical calculations. Further experimental advances may be expected from the availability of the new synchrotron sources, which allow the use of smaller crystals, harder radiation, and shorter data collection times