The determination of all the elastic constants of a supported film of thick
ness smaller than 1 mu m is an unsolved problem. Various experimental proce
dures can be found in the literature, such as nano-indentation and laser sp
ectroscopy methods based on the propagation of surface acoustic waves (SAWs
), namely Surface Brillouin Scattering (SBS) and laser-induced SAWs. For th
e first time, the elastic constants of isotropic diamond-like films (ta-C a
nd ta-C:H) have been determined by SBS from a modified Rayleigh wave and lo
ngitudinal guided mode. In SBS, the nano-mechanical response of the film is
spontaneously probed by surface acoustic phonons scattering the light beam
. A new fitting procedure gives a precise evaluation of the elastic constan
ts even in the extremely difficult case of hard on soft structures. Tn cont
rast to nano-indentation, the Young's modulus, E, is determined directly. T
his provides a useful validation of the diverse approaches adopted to analy
se nano-indentation data. (C) 2000 Elsevier Science S.A. All rights reserve
d.