The absolute small‐angle x‐ray intensities, scattered by two activated carbons, are analyzed assuming that coals scatter as polydisperse distributions of uncorrelated layered cubic particles. The specific interphase surface areas and the densities of the samples are obtained by the particle populations resulting from the intensity best‐fits. The values agree, within a factor two, with those obtained by different experimental techniques.

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By analogy with pore terminology, a particle is said to be a micro or macroparticle depending on whether its typical size is smaller than L1 or larger than L2, while in the remaining case it is said to be a mesoparticle. The values of L1 and L2 change with different authors but they are typically of the order of 10 Å and 500 Å, respectively. In the following, we shall take L1∼10 Å and L2∼300 Å.
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Consideration of the electron density instead of the electron density fluctuation is justified by the fact that the considered h values exceed 0.001 Å−1.
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L. D. Landau and E. L. Lifschitz, Electrodynamics of Continuous Media (Pergamon Press, London, 1970), Chap. XV.
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15.
Note that the D and d values reported in I, i.e., 3.5 and 1.5 Å, round-off the values 3.35 and 1.42 really used in calculating the Il(h)’s.
16.
Actually the terminology becomes correct if one imagines adding a layer of void, D—d thick, to the particle, [see Fig. 2(c) of the paper by
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18.
In order to avoid any confusion, the number of layers and the density number of the particle having the lth size are denoted, respectively, by l and Nl.
19.
We note that all the reported numerical quantities, whose determination depends on max, change very slowly as the latter increases. In fact, setting max = 1600, the largest deviation is estimated, using the population extrapolation obtained from Eq. (7), not to exceed 12%.
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