Sonochemistry in
a thin fluid layer has advantages of no visible
cavitation, no turbulence, negligible temperature changes (≲1
°C), low power transducers, and transmissibility (sound pressure
amplification) of ≳106. Unlike sonochemistry in
semi-infinite fluids, resonance and so constructive interference of
sound pressure can be established in thin layers. Constructive interference
enables substantial amplification of sound pressure at solid fluid
interfaces. Fluid properties of sound velocity and attenuation, oscillator
input frequency, and thin fluid layer thickness couple to established
resonance in underdamped conditions. In thin layer sonochemistry (TLS),
thin layers are established where ultrasonic wavelength and oscillator–interface
separation are comparable, about a centimeter in water. Solution of
a one dimensional wave equation identifies explicit relationships
between the system parameters required to establish resonance and
constructive interference in a thin layer.