Attenuation of Rayleigh Surface Waves in a Porous Material

Using acoustic microscopy at higher frequency, we show the velocity evolutions of surface acoustic waves, in particular Rayleigh waves that depend on porosity for a mesoporous silicon layer. The velocities are obtained from different V(z) curves, which are determined experimentally at a frequency of 600 MHz. The analysis of V(z) data yields attenuation that is directly dependent on porosity. On the other hand, alpha sub(N)attenuation has been modeled and allows us to investigate its influence on the velocity V sub(R) of the propagation for Bayleigh waves.