Colour centres in irradiated diamonds. I

Abstract

A theoretical calculation of the energy levels, and hence absorption spectrum, of an isolated vacancy in an otherwise perfect diamond lattice has been made. The concept of a defect molecule is introduced. This enables familiar molecular orbital theory to be applied in calculating the electronic structure of the defect. The quantitative results suggest that the observed band at 2·0 eV causing irradiated diamonds to appear blue, is due to spin and orbitally allowed electronic transitions of symmetry 1 E → 1 T 2 in the neighbourhood of isolated neutral vacancies.