EXCITED-STATES OF THE VACANCY IN DIAMOND

The Coulson-Kearsley molecular model has been applied to various forms -of the vacancy in diamond with considerable. success from the point o f view of group theory. Electron-electron interaction and configuratio n mixing are two important features of the molecular model which is re examined with the intention of explaining why the model has been so su ccessful to date. Parameters representing both one-electron and electr on-electron interactions are deduced within an empirical framework of the molecular approach and are shown to consistently explain several p roperties of both GR1 (neutral vacancy) and ND1 (negative vacancy) opt ical features. Conclusions are reached concerning the position of neut ral and negative vacancy energy levels relative to the valence-band ed ges. It is shown that optical properties of the neutral vacancy and th e negative vacancy are strongly affected by charge-transfer excitation s such that optical transitions are more probable at V- than at V0. Th e optical transition proababilities for ND1 relate strongly to GR2-8 s uch that the probability of bound excitonic transitions at V0 can beco me considerably enhanced. The molecular multiplet structure of V0 is e xtended to include the effects of electron-electron correlation with b ound excitonic states and this is shown to explain several properties of GR2-8.