Midinfrared spectra of the plastic crystal phases of t -butyl bromide-h9 and -d9

The midinfrared spectra of the two plastic phases of t -butyl bromide are identical to each other and are very similar to that of the liquid, except for small decreases in the half-widths of the bands as the temperature is lowered. It is shown that molecular reorientation and intermolecular vibrational coupling contribute to the half-widths, and the residual width is attributed to site effects.