Abstract
We measured the dispersion of the graphite optical phonons in the in-plane Brillouin zone by inelastic x-ray scattering. The longitudinal and transverse optical branches cross along the as well as the direction. The dispersion of the optical phonons was, in general, stronger than expected from the literature. At the point the transverse optical mode has a minimum and is only higher in frequency than the longitudinal mode. We show that first-principles calculations describe very well the vibrational properties of graphene once the long-range character of the dynamical matrix is taken into account.
- Received 11 September 2003
DOI:https://doi.org/10.1103/PhysRevLett.92.075501
©2004 American Physical Society