  Structural alpha relaxation in liquid orthoterphenyl is studied by means of
coherent neutron time-of-flight and backscattering spectroscopy over a large
temperature range. Not only amplitude and relaxation time but also the spectral
line shape show a significant variation with wavenumber. As expected from mode
coupling theory, these variations are correlated with the static structure
factor. Even far above the melting point, alpha relaxation remains
non-exponential.
