Synchrotron X-ray diffraction study of the incommensurate graphite-bromine compound: Change in the c-axis repeat distance during the incommensurate-commensurate transition

Synchrotron X-ray diffraction showed that the incommensurate-commensurate transition of stage-2 graphite-bromine at 319 K involved a change of the c-axis repeat distance from $\text{10.40 ± 0.01}\text{A}\text{?}$ to $\text{10.22 ± 0.01}\text{A}\text{?}$. This suggests that the transition is three-dimensional in nature and that the bromine atoms between two carbon layers in the incommensurate phase are not confined to a plane.