The hydrogen atom has one electron with specific energy levels allowed,
If the electron is at the lowest energy level -13.59, then it takes a photon with energy of more than 10.19 but less than 12.08 to send this electron definitely to the next allowed energy level of -3.40, is this right? Excess energy from the precisely allowed level will be radiated away as photon.
If the hydrogen atom's single electron is excited to very high energies, for example n=100, it is called a "Rydberg atom".
The very high energy electron results in a much "larger" radius of the hydrogen atom.
Suppose E is the energy necessary to send the electron from n=100 to n=102 level.
Then, if we place two such atoms near enough,
In this case, after successfully sending one atom to n=102 using a photon of energy E, the other atom near enough to the first atom can no longer be excitable to same level n=102 using a photon of the same energy E. A higher energy photon is needed to push it to the next energy level. The most it can settle for given E is now only to get to n=101.
I don't quite understand why this is so, if the energy level is exactly predetermined for each level, why will a nearby electron with high energy raise the energy requirement for its neighboring electron?