Numéro
J. Phys. Colloques
Volume 42, Numéro C6, Décembre 1981
International Conference on Phonon Physics
Page(s) C6-584 - C6-586
DOI https://doi.org/10.1051/jphyscol:19816170
International Conference on Phonon Physics

J. Phys. Colloques 42 (1981) C6-584-C6-586

DOI: 10.1051/jphyscol:19816170

INTERNAL AND EXTERNAL PHONONS IN MONOCLINIC TETRACYANOETHYLENE

S.L. Chaplot1, 2, A. Mierzejewski3, J. Lefebvre4, G.S. Pawley1 et T. Luty3

1  Department of Physics, University of Edinburgh, Scotland
2  Nuclear Physics Division, Bhabha Atomic Research Center, Bombay, India
3  I-4, Technical University of WrocŽaw, WrocŽaw, Poland
4  ILL, Grenoble, France


Abstract
Dispersion curves of 12 external and 10 internal phonon modes have been measured in the a*, b* and c* directions. The internal dispersion curves correspond to the 5 low-frequency vibrations of the free molecule and they exhibit a significant proportion of lattice mode character involving both translational and librational motions. Recent lattice dynamical calculations, in which several internal modes are included, have yielded neutron scattering cross-sections which have made possible to assign the observed molecular vibrations.