Rydberg series in condensed matter: a fluorescence depletion experiment

Rydberg-Rydberg transitions are induced by absorption from the lowest Rydberg state of NO A 2Σ+ (3sσ) in Ar matrices, which is excited by an ArF laser at 193.3 nm. The depopulation of the A(ν = 0) level to higher Rydberg states 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.