Micromeritics TriStar II 3020 - Cheng;Yang Correction

Appendix C TriStar II 3020
C-22 302-42828-01 - Dec 2012
T
3
=
T
4
=
where
Cheng/Yang Correction
P
Po
-------


ln GL 1
1

---
1
1 –
------------


ln––=
This factor corrects for the nonlinearity of the isotherm. It adds an additional term to the equations for
the different geometrics:
where
G(L) = one of the Horvath-Kawazoe equations given above
 = degree of void filling;  is estimated by first computing the monolayer capacity
(V
m
) with the Langmuir equation over the range of data points from relative
pressure 0.02 to 0.2 or the maximum relative pressure included in the Horvath-
Kawazoe analysis.  is computed as the quantity adsorbed over V
m
.
1
1 S–
9
-------------------
1
1 S+
9
-------------------
–
1
1 S+
8
-------------------
1
1 S–
8
-------------------
–
S
Ld
0
–
L
--------------
=