Micromeritics GEMINI VII, Руководство оператора

Страница: 223 / 253

Pores of 4 Å width, barely larger than the argon atom (3.38 Å), fill at pressures below 1 millitorr.
Pores below 15 Å fill before a monolayer is completed on the surface of the larger pores. In the
micropore size range, the pore volume fills more gradually with pressure and the total shape of the
isotherm is important in characterizing the pore size.
Models Included
Non-Local Density Functional Theory with Density-Independent Weights
N2 - DFT Model
AR - DFT Model
Geometry: Slit
Substrate: Carbon (graphite)
Category: Porosity
Method: Nitrogen at 77 K; Argon at 87 K
Using the methods of non-local density functional theory, two sets of isotherms have been
calculated to serve as kernel functions for the characterization of porous solids from adsorption
data. The model isotherms are stored in binary format files. These models assume a
slit-like pore
geometry . The pore size range from 4.0 to 4000 Å is covered in 91 classes in a geometric
progression. The class intervals are rounded to the nearest 0.02 molecular diameters. A model for
the free or external surface is included to account for unfilled pores. Each of the 92 model
isotherms has been calculated at 181 pressure points from near 1×10
-6
to near 1.00 relative
pressure.
These models are identical to those supplied with the original DOS version of DFT software.
Some slight difference from the DOS results may be noted when they are applied to the same
data due to improvements in the deconvolution algorithm and better regularization of the current
software.
Non-Local Density Functional Theory with Density-Dependent Weights
N2 - Modified Density Functional
Geometry: Free surface
Substrate: Surface energy
Method: Nitrogen at 77K
Models Based on Statistical Thermodynamics
Gemini VII Operator Manual
239-42828-01 (Rev H ) — May 2021
B - 7