Nitrogen distribution at 77.7 K in mesoporous Gelsil 50 generated via evolutionary minimization with statistical descriptors derived from adsorption and in situ SANS.

Digitized periodic material models of size 100(3) nm3 of mesoporous xerogel Gelsil 50 are reconstructed by use of an evolutionary minimization technique, with two-point probability S2(r) and volume-based pore size distribution Psi(D) as a hybrid target function. S2(r) and Psi(D) are derived from small-angle neutron scattering (SANS) and adsorption data, respectively. The nitrogen distribution in Gelsil 50 is characterized in the multilayer adsorption and capillary-condensation regimes by S2(r) and statistical parameters obtained from in situ SANS data. The fraction of liquid-free pore space varphi is calculated from nitrogen adsorption data, and the distribution Psicorr(D) of the diameter of the liquid-free pore space at certain relative pressures is derived from Psi(D). The evolutionary algorithm is also used to generate the spatial nitrogen distribution by means of the descriptors varphi, S2(r), and Psicorr(D). The morphological parameters obtained from the reconstructs are compared to the respective SANS results.