Knowledge Bank

The infrared spectra of methyl halides condensed rapidly from the vapor onto a window held at liquid nitrogen temperature have been examined from 30 to $130cm-1$. Two sharp bands are found for each compound which are interpreted as arising from the A- and B- axis librational modes of molecules on the $Cn$ crystal sites. Effects of correlation interaction are absent. The behavior of the spectra upon annealing of the deposits will be discussed and interpreted on the basis of possible structures of the rapidly rapidly condensed samples.