ON THE NATURE AND EFFICIENCY OF COLORATION OF MGF2 CRYSTALS BY 100 KEV IONS

MgF2 crystals have been implanted with a variety of 100 keV ions in th e dose range 6 x 10(15) to 1 x 10(17) cm-2. Colouration is distinctly more efficient following implantation near ambient temperature with me tallic ions (magnesium, aluminium, sodium) than with rare gas ions (ne on, argon, krypton, xenon). This is thought to be due to the different chemical nature of the implanted ions which inhibit vacancy-interstit ial recombination during implantation. Absorbance curves are presented for increasing doses of magnesium ions in MgF2. A variety of F-type c olour centre bands are observed. These include the F-centre, the F2(pi )-centre and four F2-centres which are nondegenerate owing to the ruti le structure. Extrinsic colloid bands characteristic of the implanted metallic ions form at large doses.