SIZE DISTRIBUTION OF NANOPARTICLES BY DYNAMIC LIGHT SCATTERING. COMPARISON OF BAYESIAN AND TIKHONOV INVERSION METHODS

CLEMENTI, LUIS A.; VEGA, JORGE R.; GUGLIOTTA, LUIS M.; HELCIO R.B. ORLANDE

INVERSE PROBLEMS IN SCIENCE AND ENGINEERING

TAYLOR & FRANCIS LTD

Lugar: Oxfordshire; Año: 2012 vol. 20 p. 973 - 990

1741-5977

The diameter distribution of nanometric particles is estimated from multiangle dynamic light scattering (MDLS) measurements by solving an ill-conditioned nonlinear inverse problem through Tikhonov and Bayesian methods. For both methods, the data inputs are the angle-dependent average diameters of the particle size distribution (PSD), which are in turn calculated from the measured autocorrelation functions of the light intensity scattered by a dilute sample of particles. The performance of both methods were tested on the basis of: (i) two simulated polymer latexes that involved PSDs of different shapes, widths, and diameter ranges; and (ii) two real polystyrene latexes obtained by mixing two well-characterized standards of narrow PSDs (of known nominal diameters and standard deviations). For PSDs exhibiting highly-asymmetric modes, or modes of quite different relative concentrations, the Bayesian method produced PSD estimates better than those obtained through Tikhonov regularization.