Micromeritics ASAP 2460, Operator'S Manual

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Appendix C ASAP 2460 Operator’s Manual
C-28 246-42800-01 - Aug 2013
P = equilibrium pressure
Po = saturation pressure
R = gas constant (8.31441 × 10
7
erg/mol K )
r
p
= radius of the cylindrical pore,
T = analysis bath temperature ( K ), from an entered or calculated value on the
Po
and Temperature Options
window
Sphere Pore Geometry (Cheng/Yang)
When you use the Cheng/Yang
11
method, the following equation is solved for each value of P . The
value of L is determined when the solved-for relative pressure is within 0.1% of the collected absolute
pressure.
where
10
32
= the number of cm
4
that are equal to Å
4

*
12
= , where


*
22
= , where
d
0
=
where:
D
A
= molecular diameter (Å) from the
Horvath-Kawazoe Physical Properties
window
D
S
= diameter of sample atom (Å) from the
Horvath-Kawazoe Physical
Properties
window
L = pore width (nucleus to nucleus) (Å)
N
1
= 4

L
2
N
S
, where N
S
= number of sample atoms/cm
2
at monolayer
N
2
=
4

( L - d
0
)
2
N
A
, where N
S
= number of gas molecules/cm
2
P = equilibrium pressure
P o = saturation pressure
R = gas constant (8.31441 × 10
7
erg/mol K )
T = analysis bath temperature ( K ), from an entered or calculated value on the
Po
and Temperature Options
window
L
2
---
P
Po
-------
 
 
ln
6 N
1
 *
12
N
2
 *
22
+ L
3
10
32 
RTL d
0
–
3
------------------------------------------------------------------
d
0
L
----
 
 
6
T
1
12
------
T
2
8
-----
+
 
 
–
d
0
L
----
 
 
12
T
3
90
------
T
4
80
------
+
 
 
+
=
Å
S
4 d
S
6
-------------
Å
S
6 mc
2
 
S

A

S

S
------

A

A
-------
+
--------------------------------
=
A
A
4 D
A
6
---------------
Å
A
3 mc
2
  
A
 
A
  
2
-------------------------------------------
=
D
A
D
s
+
2
--------------------