Physical principle

Laser-induced breakdown detection is a promising analytical method to detect trace amounts of nanoparticles (<100 nm) in aqueous suspensions. The measurement principle is based on a pulsed laser beam that is focused into a measurement cuvette containing nanoparticles in suspension. When the laser pulse power density exceeds a certain breakdown threshold, a breakdown of the dielectric properties occurs and subsequently a plasma forms. The breakdown and thus the formation of the plasma occur selectively on the particles as the laser power density needed to ignite a plasma in solids is lower than for liquids (solvent) and for gases (gas bubbles) and can, therefore, be used to derive the size, concentration and composition of nanoparticles in the sample.