It was used to show the first images of charge distribution over a single molecule in November 2011.
I do not understand how changes in charge distribution can take place within an atom at the rates corresponding to the frequency of light.
An electron has no charge distribution, and is therefore considered a point charge.
One physical system of this type is a charge distribution in electrostatics.
The total force is the volume integral over the charge distribution:
But, in this case, the connection between the charge distribution and the electric field frequency is less clear.
This can also be written as an integral with respect to a signed measure representing the charge distribution.
This difference induces a change in the electric charge distribution of the nucleus.
Often the charge (or mass) distribution are given, and the associated potential is unknown.
I have the feeling, however, that the coupling is not directly through space, but via a response in the electric charge distribution.