I know that an Rydberg Atom will not usually have a Dipole Moment - as the positive nucleus are surrounded by a negative electron cloud, so there is no uneven charge distribution.
However, I also know that a Rydberg Atom with experience an Electric Dipole Moment when in an Electric Field. So my question is, How does An Electric Field Create a Dipole Moment of a Rydberg Atom?
The Rydberg electron - the electron in the high n level - is highly polarizable and very weakly held. The binding energy of the electron is very small.
A small electric field will distort the wavefunction of the Rydberg electron so that it spends more time on one side of the atom than the other. The result is the formation of dipole.
Rydberg electrons in high levels are very sensitive to electric fields and easily ionized in 'field ionization' where electric fields as small as 5V /cm may pull the electrons off the atoms. This is the basis of the experimental ZEKE spectroscopy technique
