“…For cobalt, however, according to the universal trend of the position of deep levels, 6,8 the donor level lies higher, so that less energy is required for the formation of a donor exciton. It is seen that in our case ͑the donor exciton region in ZnO:Co͒, as in the acceptor exciton region of other compounds, [13][14][15][16] the vibrational replicas of the ZPL can be decomposed into a series of modes: a dominant mode ͑the first peak of which has the highest intensity͒ and two partner modes. Each mode is indicated by a different type of arrow: the solid arrows indicate the dominant mode, of the form n⍀ ͑n =1,2,3, ...͒; the long-dash and short-dash arrows indicate partner modes of the form n⍀ + i ͑i =1,2͒.…”