Figure above illustrates the spectrum of the garnet
crystal. The garnet belonging to the cubic symmetry, its spectra do not
depend upon the polarization direction of the light. The large peak at
7600 cm-1 is a crystal field transition of Fe2+
ion in a distorted 8-fold cubic site. As the symmetry of this site is no
more perfectly cubic, the Fe2+ levels are further split and
so produce transitions at higher wavelengths. As the wavelength range of
my spectrometer is limited due to detector, only the rise of the second
band at 1650 nm is barely visible. Below 600 nm, small spin forbidden
transitions in Fe3+ and Fe2+ are also visible. |