Rydberg and charge-transfer states of atomic oxygen in Ar and Kr matrices: identification of two distinct sites

The excitation spectra, between 190 and 100 nm, of atomic oxygen imbedded in Ar and Kr crystals are presented. The spectra were obtained by monitoring the 1S→1D emission in the 560 nm region. Based on the spectral shifts going from Ar to Kr matrices, which are proportional to the difference between the ionization energies of Ar and Kr, the excitation maxima at 145 and 133 nm in Ar and 179 and 162 nm in Kr are assigned to transitions involving charge-transfer upper states. Transition into the (2s22p33s) 3S Rydberg state from the (2s22p4) 3P ground state of O are also observed with a blue-shift of 0.69 eV in Ar and 0.32 eV in Kr.