Effects of phonons induced by Co2+in the far IR absorption spectrum of synthetic quartz

Abstract
A continuous far-infrared background absorption is induced in single-crystal quartz by Co2+ ions from 10 to 160 cm-1. The temperature dependence is negligible between 290K and 10K. On the other hand, three absorption maxima are observed at 40, 102 and 150 cm-1 where maxima in the density state of phonons have been observed by neutron scattering.