  We carried out micro-Raman spectroscopy of graphene layers over the
temperature range from approximately 80 K to 370 K. The number of layers was
independently confirmed by the quantum Hall measurements and atomic force
microscopy. The measured values of the temperature coefficients for the G and
2D-band frequencies of the single-layer graphene are -0.016 1/(cm K) and -0.034
1/(cm K), respectively. The G peak temperature coefficient of the bi-layer
graphene and bulk graphite are -0.015 1/(cm K) and -0.011 1/(cm K),
respectively.
