Fig. 4A, the increase of graphene layers induced the significantdecrease of Raman signal intensities of iodine anions (I3and I5),and the intensities were 30 times stronger on one layer of graphene than bulk graphite. A similar phenomenon illustrated in Fig. 4B was demonstrated in which the single layer intercalated bromine (Br2) Raman intensity in bulk graphite was 6 times bigger than in four layers of graphene.