2004/02/17 by Janina Maultzsch, J. Maultzsch, S. Reich +5 · 2 citations
Materials Science · #Graphene research and applications #Carbon Nanotubes in Composites #Diamond and Carbon-based Materials Research
paper · doi:10.1103/physrevlett.92.075501
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 \ensuremathΓ\mathrm\text\ensuremath-K as well as the \ensuremathΓ\mathrm\text\ensuremath-M direction. The dispersion of the optical phonons was, in general, stronger than expected from the literature. At the K point the transverse optical mode has a minimum and is only \ensuremath≈70 cm^\ensuremath-1 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.