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Two-Length-Scale Structure in Some Computer-Generated Aggregates Grown by Diffusion-Limited Aggregation

Published online by Cambridge University Press:  03 September 2012

Paul W. Schmidt
Affiliation:
Department of Physics and Astronomy, University of Missouri--Columbia, Columbia, MO 65211, USA
Giuseppe Pipitone
Affiliation:
Department of Physics and Astronomy, University of Missouri--Columbia, Columbia, MO 65211, USA
M. A. Floriano
Affiliation:
Dipartimento di Chimica Fisica, Università di Palermo, Via Archirafi, 26, 90123 Palermo, Italy
E. Caponetri
Affiliation:
Dipartimento di Chimica Fisica, Università di Palermo, Via Archirafi, 26, 90123 Palermo, Italy
R. Triolo
Affiliation:
Dipartimento di Chimica Fisica, Università di Palermo, Via Archirafi, 26, 90123 Palermo, Italy
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Abstract

The properties of some aggregates “grown” on a computer by diffusion-limited aggregation have been investigated. Calculations showed that the intensity of the small-angle x-ray and neutron scattering from the aggregates was proportional to q−D for qL ≫ 1, where D > 0, L is a length that characterizes the large-scale structure of the aggregate, q = 4πλ−1 sin(θ/2), γ is the wavelength, and θ is the scattering angle. The magnitude of the exponent D was appreciably smaller than the fractal dimensions that many simulations have shown to be typical of the mass fractal aggregates grown by diffusion-limited aggregation. The calculations suggest that the aggregates have structure on two different characteristic-length scales.

Type
Research Article
Copyright
Copyright © Materials Research Society 1995

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