Effects of liquid loading on surface acoustic waves in solids

We study the effect of liquid loading on the characteristics of surface acoustic waves propagating along the (100) surface of silicon. A nonviscous liquid layer of infinite thickness in contact with a solid substrate causes changes in the wave velocity and the attenuation of surface waves along the liquid-solid boundary. More importantly, we examine an additional branch of the Rayleigh surface that is induced by the liquid loading. We also find that the pseudosurface wave, which is restricted only to certain directions on the free surface, extends to all directions on the liquid-loaded (100) surface. Calculating the acoustic Poynting vectors associated with these surface-related acoustic modes, we find that the Rayleigh wave and the induced Rayleigh wave emit energy only into the liquid, whereas the pseudosurface wave emits energy both into the liquid and solid substrate.