M. Carpineti et al., CORRELATION AND ANTICORRELATION OF FRACTAL AGGREGATES - A MODEL FOR [[SPINODAL-TYPE]] AGGREGATION, Nuovo cimento della Societa italiana di fisica. D, Condensed matter,atomic, molecular and chemical physics, biophysics, 16(8), 1994, pp. 1243-1246
We present a simple phenomenological model, based on mass conservation
arguments, in order to describe aggregation in dense solutions. It ha
s been previously shown that for diffusion-limited processes scattered
intensity distributions exhibit a peak at q not equal 0 which grows i
n time and moves to smaller and smaller q vectors. According to the mo
del, each aggregate is surrounded by a depletion region whose size dep
ends on the aggregation kinetics. The form factor for such a cluster s
hould satisfy local mass conservation and hence exhibit a pronounced d
epression at q = 0. The initial stages of aggregation, when the cluste
rs are far apart, are accounted on the basis of a form factor alone. T
he model shows good agreement with the data and also explains the expe
rimental evidence that the peak does not appear in reaction-limited co
nditions.