"The experiment, outlined in a new paper,* would not only mean more accurate identifications of elements in everything from stars to environmental pollutants but also could put the modern theory of the atom to the most stringent tests yet."

"NIST researchers Joseph Tan and colleagues hope to implement this approach experimentally in their Electron Beam Ion Trap Facility. The idea would be to strip an atom of all its electrons, cool it and inject a single electron in a high-flying orbit. Then the researchers would use a sensitive measurement device known as a frequency comb to measure the light absorbed by this Rydberg atom. The result could be an ultraprecise frequency measurement that would yield an improved value for the Rydberg constant. Such a measurement would be so sensitive that it could reveal anomalies in quantum electrodynamics, the modern theory of the atom."