EFFECTS OF IMPLANTATION DOSE ON THE INHOMOGENEOUS BROADENING OF ZERO-PHONON LINES IN LIF

The inhomogeneous broadening and line shape of the F4 (1) zero phonon line in LiF at 2.366 eV, measured at 4 K, has been used to probe the e nvironment of these defects and the presence of internal strain as a f unction of implantation dose. Measurements on LiF implanted with 1 MeV protons at room temperature show substantial broadening of the zero p honon line. Studies of low and high dose gamma-irradiated samples are used for comparison purposes. The observed broadening in the proton im planted specimens shows irregularities which is compared with the grow th and collapse of colour centre concentrations previously reported in the literature. The results suggest two regimes: a low dose region wh ere broadening results from point defects and small point defect aggre gates and a high dose region where extended defects are, to a signific ant extent, responsible. Line shape analysis is consistent with these conclusions.