Magnetic and uniaxial stress perturbations of optical transitions at a four Li atom complex in Si

Zeeman measurements are reported on the 1044 and 1045 meV lines of a Li centre in Si, showing that the lower-energy line involves a spin triplet excited state and the higher-energy line a spin singlet excited state. Uniaxial stress data are analysed to show that the transitions occur at a trigonal centre and have orbital Gamma 3 excited states with properties very similar to the valence band and conduction band extrema of Si.