  We report on far infrared measurements on Zn and Si doped crystals of the
spin-Peierls compound CuGeO3. Zn doping has the effect of introducing several
new absorption lines, polarized in the ab-plane, between 5 and 55 cm-1. The
intensity of the absorption grows with Zn concentration but saturates above 2%
Zn. One line at 10 cm-1 loses intensity above 4K, and a second line at 20 cm-1
is absent at low temperatures but grows to peak at about 40K in agreement with
a three level model with two excited states 10 and 30 cm-1 above the ground
state. As the doping is increased these lines broaden, and a temperature
independent absorption developes over the entire range from 5 to 55 cm-1. These
features are magnetic field independent up to 16T and are absent in Si doped
samples. We suggest the new absorption is due to localized lattice modes of the
zinc ion and the surrounding GeO4 tetrahedra.
