Micromeritics Gemini VII 2390a, Operator'S Manual

Page: 362 / 426

Appendix F Gemini VII
F-16 239-42828-01 - Dec 2012
Kelvin Equation with Broekhoff-de Boer Thickness Curve
N2 - Broekhoff-de Boer Model
The kernel function is calculated using the Broekhoff-de Boer equation with standard parameters:
The nitrogen properties used in the Kelvin equation are:
N2 - Broekhoff-de Boer Model
The calculation is similar to the above except that cylindrical geometry is assumed, and the film thick-
ness depends on pore size (see reference).
Geometry
Slit
Substrate
Average
Category:
Porosity
Method:
Nitrogen at 77 K
Surface tension =
8.88 dynes cm
-1
Molar density =
0.02887 g cm
-3
Geometry
Cylinder
Substrate
Average
Category:
Porosity
Method:
Nitrogen at 77 K
Reference
: Specifically, equations 20 and 21 in: J.C.P. Broekhoff and J.H. de Boer,
“The Surface Area in Intermediate Pores,” Proceedings of the
International Symposium on Surface Area Determination, D.H. Everett,
R.H. Ottwill, eds., U.K. (1969).
p
/
p
0
 
16.11 –
t
2
---------------- 0.1682
0.1137
t
–
+ = log