Micromeritics ASAP 2460 - Horvath-Kawazoe; Slit Pore Geometry (Original HK

Appendix C ASAP 2460 Operator’s Manual
C-26 246-42800-01 - Aug 2013
where
ΔV
p
= Change in pore volume
A
p,i
= Pore surface area
A
p,i,cum
, l
i,cum =
Summations over the lengths and areas calculated so far
C
v
= Volume correction factor
D= Density conversion factor
= Average Kelvin radius
= Average thickness
Horvath-Kawazoe
A relative pressure lower limit is determined such that L-d
0
never equals zero. All pressure points less
than this limit are discarded. For each collected relative pressure point, values of L are chosen in an
iterative manner, and the relative pressure (P/Po) determined by solving one of the following
equations:
• Slit Pore Geometry (original Horvath-Kawazoe)
• Cylinder Pore Geometry (Saito/Foley)
• Sphere Pore Geometry (Cheng/Yang)
Slit Pore Geometry (original HK)
When you use the original Horvath-Kawazoe
9
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
 = gas solid nuclear separation at zero interaction energy (Å),
d
0
=
where:
D
A
= molecular diameter (Å) from the Horvath-Kawazoe Physical Proper-
ties window
D
s
= diameter of sample atom (Å) from the Horvath-Kawazoe Physical
Properties window
r
k
t
P
Po
-------ln
K
RT
-------
IP 10
32


4
L 2d
0
–
------------------------

4
3Ld
0
–
3
--------------------

10
9Ld
0
–
9
--------------------
–

4
3d
0
3
----------
–

10
9d
0
9
----------
+=
Z
S
Z
A
+
2
-------------------
D
A
D
s
+
2
--------------------