Micromeritics Gemini VII 2390a, Operator'S Manual

Page: 313 / 426

Gemini VII Appendix C
239-42828-01 - Dec 2012 C-19
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)
P
Po
------- ln
K
RT
-------
IP
10
32
JA
4
/
J cm
4


4
L
2
d
0

–
  
--------------------------------------------------- 

4
3
L d
0
–
 
3

-------------------------------

10
9
L d
0
–
 
9

-------------------------------
–

4
3
d
0
3

----------------
–

10
9
d
0
9

----------------
+

=
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
K = Avogadro’s number (6.023 x 10
23
)
R = gas constant (8.31441 x 10
7
ergs/mole K)
T = analysis bath temperature (K), from an entered or calculated
value on the Po and Temperature Options dialog

= gas solid nuclear separation at zero interaction energy (Å),
where:
Z
S
= sample equilibrium diameter at zero interaction energy (Å) from the Horvath-
Kawazoe Physical Properties dialog
Z
A
= zero interaction energy diameter from the Horvath-Kawazoe Physical

Properties dialog
d
0
=
Z
S
Z
A
+
2
------------------
D
A
D
S
A
 
+
2
-------------------------------