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 i n Ar and Kr crystals are presented. The spectra were obtained by monitoring the S-1 --> D-1 emission in the 560 nm region. Based on the spectral shift s going from Ar to Kr matrices, which are proportional to the difference be tween the ionization energies of Ar and Kr, the excitation maxima at 145 an d 133 nm in Ar and 179 and 162 nm in Kr are assigned to transitions involvi ng charge-transfer upper states. Transition into the (2s(2)p(3)3s) S-3 Rydb erg state from the (2s(2)2p(4)) P-3 ground state of O are also observed wit h a blue-shift of 0.69 eV in Ar and 0.32 eV in Kr. (C) 1999 Elsevier Scienc e B.V. All rights reserved.