Rydberg series in condensed matter: A fluorescence depletion experiment

Rydberg-Rydberg transitions are induced by absorption from the lowest Rydberg state of NO A(2) Sigma(+) (3s sigma) in Ar matrices, which is excited by an ArF laser at 193.3 nm. The depopulation of the A(upsilon = 0) level to higher Rydberg stares is probed by depletion of its fluorescence. Absorption bands are observed in the 1.0-2.0 eV region which are attributed to transitions to the 3p, 3d, 4s and 4p members of the Rydberg series. At higher energies, a continuous absorption structure appears. It is attributed to transitions to the n > 4 members of the Rydberg series which are compressed in a tiny energy range below the ionization potential. A quantum defect model is applied and accounts well for the observations.