Micromeritics TriStar II 3020 - MP-Method

TriStar II 3020 Appendix C
302-42828-01 - Dec 2012 C-33
MP-Method
t
I
HP1
HP2
P
rel
I
ln
---------------------

HP3
=
For each point designated for MP-method
14
calculations, the following calculations are done:
Thickness for the I
th
point (Å):
(Halsey
5
)
t
I
HJP1
HJP2 P
rel
I
log–
--------------------------------------------
HJP3
=
or
(Harkins and Jura
6
)
where:
t
I
= thickness for I
th
point
HP1 = Halsey parameter #1
HP2 = Halsey parameter #2
HP3 = Halsey parameter #3
HJP1 = Harkins and Jura parameter #1
HJP2 = Harkins and Jura parameter #2
HJP3 = Harkins and Jura parameter #3
P
relI
= relative pressure for the I
th
point (mmHg)
With the (t
I
,V
I
) data pairs, the Akima semi-spline interpolation method is used to interpolate quantity
adsorbed values based on thickness values that are evenly spaced 0.2 Angstrom apart starting at the
first outlier point. Outliers are defined as those points have the maximum instantaneous slope within an
iteratively shrinking subset of all points. The remaining pore surface area calculation result is the slope
of the line defined by two consecutive interpolated points. The slopes of each pair of consecutive
points from the origin to the last point must be monotonically decreasing and non-negative. With the
interpolated points set the following can be calculated:
Average pore hydraulic radius (Å):
R
I
t
I
t
I 1–
+
2
--------------------
=