Knowledge Bank

Recent unpublished measurements made in this laboratory on the infrared and Raman spectra of selected crystals will be reported. In order to enable complete assignments to be made for $k=0$ vibrations, spectra have been recorded over a wide temperature range throughout the region $10cm-1$ to $10,000cm-1$ using polarized radiation. The dielectric parameters $ϵI\prime$ and $ϵII″$ have been calculated from the reflection spectra and their variation with frequency will be compared with theory. The nature of the damping factor $I\prime$ will be discussed. Some observations on the problem of obtaining good Raman spectra of single crystals will be made.