Cavitation induced Becquerel effect.

Area of Science:

• Physical Chemistry
• Electrochemistry
• Acoustics

Background:

• The Becquerel effect, an electrical current from UV illumination of electrodes in water, was observed over 150 years ago.
• A related phenomenon, the cavitation-induced Becquerel effect, generates current when water around an electrode cavitates due to acoustic radiation.

Purpose of the Study:

• To investigate the mechanism behind the cavitation-induced Becquerel effect.
• To determine if the current is due to photo-emission or photo-decomposition theories.

Main Methods:

• Analysis of the current's semi-logarithmic relationship with standard electrode potential.
• Investigating the role of cavitation-induced UV light and potential electrode oxidation.
• Exploring the spontaneous emission of coherent infrared (IR) radiation within bubbles as a source of vacuum ultraviolet (VUV) radiation.

Main Results:

• The observed current characteristics align with the photo-decomposition theory, not photo-emission.
• High bubble collapse temperatures are unlikely to be the primary cause of electrode oxidation.
• A novel mechanism is proposed where IR emission, amplified by cavity quantum electrodynamics, generates VUV radiation that excites OH* states, leading to electrode oxidation.

Conclusions:

• The cavitation-induced Becquerel effect is explained by a photo-decomposition mechanism driven by VUV radiation generated from IR emission within bubble walls.
• This process involves excited OH* states reacting with the electrode surface at ambient temperatures.