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. Electron paramagnetic resonance
(EPR) spectra measurements were carried out with a
Bruker EMX spectrometer. The spectra were recorded
at X-band with 100-kHz field modulation at RT. Optical
absorption (OA) spectra were registered using unpolarized
light with a Cary 500 spectrometer at RT, and
thermoluminescence (TL) in a Daybreak TL reader with
a heating rate of 2 8Cys. Irradiation of the samples was
carried out at RT using a 60Co source.