## Mnv

x0 y

where x0 = exp[(e0 -ec)/kT], r0 = exp[-F(e0)] and e0 is a constant. Equation (6.62) is equivalent to Equation (6.56), except that the coefficient [kT ln(x/x0)]2 depends linearly on the fractal dimension A.

One of the assumptions underlying the theory described above was that the lower fractality range was zero. The problem of the limits [Rmin, Rmax] has already been discussed in Section 6.3. While accepting the 'classical' pore size distribution, Equation (6.41), along with its limited range of applicability, [Rmin, Rmax], one can describe only a part of the experimental isotherm corresponding to pressures in the relevant range [pmin, pmax]. To derive an isotherm equation that could be valid over the entire range of pressures, Rudzinski et al. [89, 90] considered a new model of geometrical heterogeneity, according to which real adsorbents are never totally irregular (fractal) and never perfectly regular, but instead they have a structure that is intermediate between the two extremes. The isotherm for such adsorbents, which were named 'partially correlated', has the form ln

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