Nanoparticle sizing by a laser-induced breakdown detection using an optical probe beam deflection

A method for determining the size of a colloidal nanoparticle by measuring the magnitude of the probe beam signal which can be remotely measured in a non-contact manner has been developed. The method using a probe beam signal is intended to employ a principle by which the path of a probe beam is changed by a laser-induced shock wave, accompanying the occurrence of a laser-induced breakdown of colloidal nanoparticles. It was observed that the peak and full width at half-maximum of a frequency distribution curve of the measured magnitude of a probe beam signal appear in direct correlation with the size of a nanoparticle at the fixed pulse energy of a laser beam for the breakdown. A calibration curve for a particle sizing is presented for particle diameters ranging from 20 to 60 nm, with reference polystyrene particles. An application is demonstrated for measuring hexavalent uranium colloidal particles generated by the hydrolysis of free uranyl ions.