  Grazing incidence fast atom diffraction at crystal surfaces (GIFAD or FAD)
has demonstrated coherent diffraction both at effective energies close to one
eV ($\lambda_\perp\approx$ 14 pm for He) and at elevated surface temperatures
offering high topological resolution and real time monitoring of growth
processes. This is explained by a favorable Debye-Waller factor specific to the
multiple collision regime of grazing incidence. This paper presents the first
extensive evaluation of the temperature behavior between 177 and 1017 K on a
LiF surface. Similarly to diffraction at thermal energies, an exponential
attenuation of the elastic intensity is observed but the maximum coherence is
hardly limited by the attraction forces. It is more influenced by the surface
stiffness and appears very sensitive to surface defects.
