The samples were cut into slabs of 6=8=1 mm3 and polished with the surfaces perpendicular (PEE) and parallel (PAE) to the optical c-axis. Ion implantation was performed with energy of 400 keV at room temperature (RT) for all samples. For Fe, Mn and Cr, the implanted dose was 2=1016 ionsycm2 and for V it was 9=1015 ionsycm2. After ion implantation, the samples were annealed at 500 8C for 1 week.
Rutherford backscattering spectroscopy (RBS) showed that the ion range for Fe was 257 nm for the parallel and 272 nm for the perpendicular slab.
For Mn, this was 248 and 263 nm, for Cr it was 233 and 245 nm and for V it was 263 and 251 nm, respectively.
The implantation of V, Cr, Fe and Mn ions into
samples of beryl does not cause appreciable changes in
the coloration of the crystal, but causes new defects,
such as a loss of charge of Fe3q and Mn2q ions, as
shown by EPR measurements, an increase in Fe2q ions,