Definitions for "Rydberg"
Rydberg is a lunar impact crater that is located on the far side of the Moon, just past the southwestern limb. It lies due south of the Mare Orientale, in the outer skirt of ejecta that surrounds the Orientale impact feature. Just to the southeast is the Guthnick crater.
a wave number characteristic of the wave spectrum of each element
Keywords:  atomic, energy, unit
Unit of atomic energy = 13.6 eV