The 12 external and the 4 lowest internal phonon dispersion branches in d₁₀-anthracene at 12K

Abstract

By inelastic neutron scattering from deuterated anthracene the authors determined the 16 lowest dispersion branches (including 4 internal modes) in the symmetry directions ( xi 00), (0 xi 0) and (00 xi ) and 5 doubly degenerate branches in the (0.5 xi 0) direction. The results agree reasonably well with optical data. Lattice dynamical calculations including the lowest intramolecular modes by first-order perturbation theory agree qualitatively with the experimental results.