Laser Induced Breakdown Detection (LIBD)

Development of a Laser Induced Breakdown Detection (LIBD) system for fast on-line analysis of nanosized materials in the environment

The LIBD technique has been introduced approx 20 years ago by Japanese researcher and is a very promising technique to detect particles (>10nm) at very low concentrations.

In this technique, a pulsed laser beam is focused in a measurement cuvette containing the particles in suspension. When the laser pulse power density exceeds a certain threshold (particle size dependent), the particle explodes and forms a plasma. If a breakdown event occurs given that the power density of a certain particle size is exceeded, only depends on the number concentration of the respective particles. The explosive expansion of the plasma generates a shockwave which can be detected by a piezo-receiver. Alternatively, the light emission can be detected using a CCD camera.

The LIBD is not commercially available, but in collaboration with the group of Prof. D. Günther, http://www.analytica.ethz.ch/group_members.htm) and with the help of Dr. T. Wagner (FZ Karlsruhe) we were able to construct our own LIBD prototype. To extend the dynamic range of the optical detection limit towards higher concentrations we are currently developing a new algorithm.