Rydberg states in condensed phases: Evidence for small ’’bubble’’ formation around NO 3sσ (A 2Σ+) in solid rare gases

Abstract

The lowest Rydberg state of NO has been observed to fluoresce with unity quantum yield in solid Ar, Kr, and Xe hosts. The purely radiative lifetimes lengthen in the sequence vacuum, Ar, Kr, Xe, thus directly demonstrating an increasing delocalization of the Rydberg wavefunction in media with increasing dielectric coefficient. A simple, semiquantitative theory of the relative stability of bubble and Wannier Rydberg states favors bubble (∼10 Å diameter) formation around low n Rydberg states in the lighter rare gas solids. Asymmetric phonon contours in absorption and fluoresence, as well as the experimental extent of delocalization compared with Wannier model predictions, both support bubble formation around NO 3sσ (A 2Σ). Sequential two photon excitation spectra from 3sσ to higher Rydberg states near 7.5 eV are broad in all three hosts. The Rydberg 3sσ spectra and photophysics are compared with those of the nearly isoenergetic B 2Π and a 4Π states in both 14NO and 15NO. Rydberg–valence perturbations in the solid phase, as well as the difference between vertical and adiabatic solid phase ionization, are also discussed.