Sphere Pore Geometry (Cheng/Yang - Micromeritics TriStar II 3020 Operator's Manual

TriStar II 3020

Sphere Pore Geometry (Cheng/Yang)

When you use the Cheng/Yang
value of L is determined when the solved-for relative pressure is within 0.1% of the collected absolute
pressure.

6 N
 
P
------ - --------------------------------------------------------------------------------------------------------- -
ln =
 
Po
6
d
1
  
0
---- - ----- - T
–
  
12
L
where
R =
T =
d =
0
where:
D
A
D
S
L =
P =
Po =
N =
1
N
=
2
e* =
12
*
=
22
T =
1
T =
2
302-42828-01 - Dec 2012
11
method, the following equation is solved for each value of P. The
* * 3 32
  L 
+ 10
N J A
1 12 2 22
3
 
–
RT L d
0
12
d
1 1 1
   
0
-- - T ---- - ----- - T ----- -
+ + +
   
1 2 3
8 90 80
L
gas constant (8.31441 x 10
analysis bath temperature (K), from an entered or calculated value on the Po
and Temperature Options dialog
A  
+
D D
A S
---------------------------- -
2
= molecular diameter (Å) from the Horvath-Kawazoe Physical Properties
dialog
= diameter of sample atom (Å) from the Horvath-Kawazoe Physical dialog
pore width (nucleus to nucleus) (Å)
equilibrium pressure (mmHg)
saturation pressure (mmHg)
2
4 L N , where N = number of sample atoms/cm
S S
2
4 (L - d ) N , where N
0 A

6 MC
A
, where
S
------------ - ---------------------------------------------- -
=
A
6 S
4d
S

3 MC
A
, where
A
-------------- - ---------------------------------------------- -
=
A
6 A
4D
A
1 1
------------------ - -------------------
–
3 3
   
1 S – 1 +
S
1 1
------------------- ------------------ -
–
2 2
   
1 + 1 S –
S
4 4
/J cm

T

4
7
ergs/mole K)
= number of gas molecules/cm
s
2
   
S A
 
S A
----- - ------
+
 
S A
2
   
A A
2
Appendix C
2
at monolayer
2
C-21