TPDSci Particle shape by LD

Particle shape by laser diffraction

PSD is routinely determined with laser diffractometers (for example, Black et al 1996). These instruments invert a two-dimensional distribution of intensity of light diffracted (scattered) by particles in a laser beam. Most laser diffractometers measure the shape of the diffraction pattern only as a function of the scattering angle, assuming that the diffraction pattern is axially symmetrical. This is sufficient for spherical particles.

However, for nonspherical particles, the effects of particle shape and orientation result in a non-axially symmetrical diffraction pattern and thus introduce errors in the inversion (for example, Matsuyama et al 2000, Naito et al 1998). The dependence of the diffraction pattern on the particle shape has been used to evaluate both the PSD and shape distribution by using laser diffractometers (for example, Ma et al 2000) with suitably designed detectors. However, the inversion process based on the use of particle shape-dependent diffraction calculations is rather complicated.

Some time ago, Coppens et al (2000) demonstrated that a neural network (NN; for example, Bishop 1994) could be succesfully used to obtain the PSD and shape distribution for suspensions of ellipsoids with a suitably designed laser diffractometer. This approach does not require the knowledge of the particle shape-dependent diffraction but uses sample diffraction patterns as training sets for the NN. Deriemaeker and Finsy (2005) continue that work to show that the average particle shape (aspect ratio) can be efficiently determined for ellipsoids which permits the determination of the particle volume distribution.

CITATION:
Jonasz M. 2006. Particle shape by laser diffraction (www.tpdsci.com/Tpc/PtShpByLD.php). In: Top. Part. Disp. Sci. (www.tpdsci.com).

HISTORY:
Published: 17-Jan-2006
Modified: 03-Jul-2006
Peer-reviewed: PENDING

Topics in Particle and Dispersion Science