Analysis of Sonoluminescence Signal from Megasonic Irradiated Gas-Containing Aqueous Solutions Using Replaceable Single-Band Filters

Abstract

A simple method to resolve the features that are characteristic of hydroxyl radicals in sonoluminescence (SL) spectra from aqueous solutions has been developed. Using a modified version of cavitation threshold (CT) cell in which single band filters were sandwiched between the UV grade fused silica window and the photomultiplier tube (PMT) in the cell, photon emission in the wavelength range of 280 to 400 nm was measured. Four different single band filters, 280-305.5 nm, 300-340 nm, 335-375 nm and 374.5-397.5 nm were used. The results for air and Ar saturated DI water are consistent with those reported in the literature and obtained using expensive spectrometers. The SL signal collected in ammonium hydroxide solutions indicated that at higher power densities the signal intensity may not be relatable to the generation rate of hydroxyl radicals in their ground state.

Detection of HO₂•/O₂•^- Radicals Formed in Aqueous Solutions Irradiated with Megasonic Waves Using a Cavitation Threshold (CT) Cell Set-Up

“…Immediately after preparation, MCLA containing solutions were transferred to a Cavitation Threshold (CT) cell for acoustic irradiation at ~ 0.93 MHz. A detailed description of the cell appears elsewhere [12]. Figure 1 shows a schematic of the modified CT cell set-up to enable simultaneous measurement of CL spectrum and photon emission.…”

Estimation of the Generation Rate of H· Radicals in a Megasonic Field Using an Electrochemical Technique

“…While many studies on the characterization of hydroxyl and hydroperoxyl radicals have been reported [5][6][7], the detection and quantitation of hydrogen radicals formed in aqueous solution during sonication have not received much attention. In the detection of HO2• and H• radicals, their reaction with cupric (Cu 2+ ) ions has been recognized.…”