Tool for studying the elastic properties of thin layers and multilayers: Brillouin spectroscopy

Some general features concerning inelastic light scattering by hypersonic w aves are exposed and it is shown that Brillouin spectroscopy can be fruitfu lly applied in order to study the elastic proper-ties of thin and ultrathin films as well as of multilayers and superlattices. A brief presentation of the various kinds of surface waves and of the mechanisms which monitor the scattering by these excitations is provided. Examples concerning transpare nt and opaque structures are given. The important influence of the interfac es is pointed out.