Commensurate-incommensurate transition and disordering in dilute graphite-bromine

Results of a x-ray scattering study of the inplane ordering in dilute graphite-bromine in the temperature range from 300 to 400K are presented. Evidence is obtained for a commensurate-incommensurate transition which is found to behave differently from those observed in the case of adsorbed monolayers. The bromine layers undergo continuous order-disorder transition from the incommensurate phase at 374K. Implications of this result and the large value of the measured exponent (β=0.32) are discussed.