New Technique for Measuring Nanoparticles

A new dynamic light-scattering technique can enable researchers to accurately determine the diameter of semiconductor nanoparticles in solution.

The technique, called noninvasive back-scattering (NIBS), uses a helium-neon laser to illuminate the sample and uses back-scattering optics to collect the light scattered by the particles. It can be used to measure particles with diameters between 1nm and 6,000 nm and has advantages over traditional methods such as transmission electron microscopy (TEM) and x-ray diffraction. NIBS can accurately determine the diameter of particles in high concentration samples, such as suspensions and emulsion, without the need for dilution.

Researchers at the Institute of Nanotechnology in Karlsruhe (Germany) used the NIBS-based high-performance particle sizer (HPPS) developed by Malvern Instruments (Malvern, UK) to determine the diameter of cadmium selenide nanocrystals and cluster molecules. Other applications include the measurement of dilute solutions of proteins and concentrated slurries such as silicas and pigments.

"The physical properties of cadmium selenide nanocrystals depend strongly on their size, so a precise method of size measurement is essential,” said Dr. Carsten von Hanisch, of the Institute of Nanotechnology.