Determination of particle size distributions with angstrom resolution

An analytical ultracentrifugation technique for the determination of particle-size distributions is used which applies an ultracentrifuge with a scanning absorption optical system. Radial scans during a sedimentation velocity experiment yield the particle-size distribution. If the particles consist of several defined monodisperse species, we show that for dense inorganic colloids the resolution of the particle-size distribution is in the angstrom range. This is demonstrated for a Pt colloid (0.4-2 nm) and unstabilized ZnO (4-9 nm) during particle growth. Such highly resolved particle-size distributions show that the analytical ultracentrifuge is an excellent and rapid tool for the study of particle growth mechanisms as no other fractionating analytical technique with almost atomar resolution is known up to now. Some potential applications arising from the applied ultracentrifuge technique are suggested.