Size Measurement of Microparticles in Liquids Using Photoacoustic Spectroscopy

Abstract

The size measurement method for microparticles in liquids using the phase shift of photoacoustic signals theorized in our earlier paper [J. Appl. Phys., 58, 1456 (1985)] was verified using polystyrene turbid solutions. The experimental values for polystyrene microparticles, radii 0.4-5.2 μm, agreed with the theoretical values within the experimental accuracy of ±0.2 deg. The physical meaning of the phase shift was clarified as representing the delay angle of the photoacoustic signal generation determined by the ratio of the heat release time from the microparticles to the modulation period of the excitation beam.Applications of photoacoustic spectroscopy for sizing and determination of microparticles in liquids by proper use of modulation frequency are discussed.