P23 電気化学計測による超音波反応場ハーモニック成分の検出(ポスターセッション)

抄録

In recent years, there has been a great deal of attention paid to problems relating to nonlinear acoustics in ultrasound fields. In this study, an alternative method is proposed for the determination of the acoustic harmonic components using the voltammetric electrode as an acoustic probe. The electrochemical reduction current of 1mM ferricyanide in KCl supporting electrolyte increased significantly in the presence of ultrasound irradiation due to an extremely enhanced mass transport. Under the ultrasound irradiation, the transient response and the a.c. components of the current were measured with digital oscilloscope, and the data was then analyzed by fast Fourier transform (FFT). Several harmonic components, 2f_0, 3f_0 and 4f_0 were observed in FFT spectrum besides the fundamental frequency. Although the detailed mechanism for sound response at the electrode has not been very clear, the electrode seems to be available for sensing the tiny acoustic pressure oscillation with high sensitivity in aqueous solution. It thus facilitated for in situ monitoring the noise generations in ultrasonic fields. Evidence shows that the harmonic components depended strongly on the experimental parameters, such as output power, the exit of cavitational bubbles or other microparticles, the distance separating from the ultrasonic source or the reflection of waves from boundaries. These effects were examined in the present study.