D. effects and N2 co-doping of Kr solids doped with NO allow continuous tuning of the NO Rydberg state energies in a range 0.35 to 0.68 eV blue of the gas phase. This property is exploited to control the vibronic configuration mixing between the Rydberg C2P and the valence B2P states. The influence on the interference lineshapes resulting from the interaction of discrete valence bands with the broad multiphonon Rydberg bands is discussed in terms of ests. of the Fano indexes. [on SciFinder (R)]