Abstract
AqueousCoumarin (0.1mmol/l) was exposed to ultrasound (US) with 500 kHz as applied to use as probe to evaluate the ultrasonic medium. After US exposed, absorption spectra of the probe were measured at different exposure times. But the coumarin band in the spectra was bleached by the exposure. Also, it was observed influorescence spectra of the probe that umbelliferone was appeared after exposing the US. This implied OH radical reacted with coumarin to born umbelliferone.
