  Oxygen molecules are found to exhibit non-negligible reactivity with graphene
under strong light irradiation in the presence of water. The reaction is
triggered by the laser Raman spectroscopy measurement itself, and the D band
(ca. 1340 cm-1) becomes larger as the laser irradiation is prolonged. The
electronic transport properties of the graphene derivative are also
investigated and both the electron and hole mobility are found to be reduced.
These results are attributed to oxidation of graphene. This primitive
modification method can be exploited to manipulate the structural and
electronic properties of graphene.
