  The dynamics of photocarriers in reduced graphene oxide thin films is studied
by using ultrafast pump-probe spectroscopy. Time dependent differential
transmissions are measured with sample temperatures ranging from 9 to 300 K. At
each sample temperature and probe delay, the sign of differential transmission
remains positive. A fast energy relaxation of hot carriers is observed, and is
found to be independent of sample temperature. Our experiments show that the
carrier dynamics in reduced graphene oxide is similar to other types of
graphene, and that the differential transmission is caused by phase-state
filling of carriers.
