Column
Penetration depth (effective thickness)
The following formula gives the ratio
Gx
between the intensity
of
diffracted X-rays from a sample
of
infinite
thickness and the intensity
of
diffracted X-rays from a sample with a specific finite thickness
ofx
(cm).
Substitute the values for angle
Bofthe
incident
X-
ray beam and X-ray absorption coefficientµ (/cm) in the
following formula to obtain
x, the effective thickness.
-ln(l-G
x)sin O Kx sin O
X=
=------
2µ
2µ
Di
ffracted X-ray
50 75 90 95 99 99.5
utilization rate
Gx
(%)
Kx
0.69 1.39 2.30 3.00 4.61 6.91
The following table shows the results
ofcalcu
lations
of
the sample thicknesses x that give a diffracted X-ray usage
rate
of90%
when K, = 2.30 and 8 = 90°.
Density
p
Mass
aboorption
coeffi<ient
IJ}p
(cm
2
/g)
T
hickn
ess
for
90%
utilization
rate
(mm)
Subotance
(g/cm
3
)
Mo
Ka
CuKa
Co
Ka
Cr
Ka
Mo
Ka
C
uKa
Co
Ka
Cr
Ka
a-AJ
,o
,
3.
97!2
3.34
31.1
48.0 97.6
1.
74 0.187 0. 12 1 0.060
Si
2.42!2
6.44 60.6
93.3
189
1.
48
0.157 0. 102 0.050
a-Si02
2.65!2
3.
71
34.5
53.
1 108 2.34
0.252 0. 164
0.080
caco,
2.71!2 8.02
70.9 107 205
1.
06 0.1
20
0.079 0.041
Powder
a-Fe
2
0
3
5.
2612
27.3 216 4
2.
7
86.5 0.160 0.020 0.
103
0.051
ZnO 5.60/2 44.7
50.7 78.2 159 0.092
0.
081
0.053 0.026
Ag,0
7.22!2 24.1 204
300
548 0.
132
0.016
0.01 1 0.0058
PbO !(tetragonal)
9.53!2
112
216 3
11
540 0.022 0.011 0.0078 0.0089
Al 2.70
5.
16
48
.6
74.
8
152
0.826 0.088 0.057
0,028
a-Fe
7.86 38.5 308 52.8
108
0.038
0.0048 0.028 0.014
Metal
SUS( l
&-8)
7.93
37.9 278
110
106
0.038 0.0052 0.013
0.014
Cu
8.92 50.9 52.9
81.6
166
0.025 0.024 0.016 0.0078
Pb
11.34
120 232 334
579
0.0085 0.0044 0.0030
0.0018
Polyethylene
0.93
0.59 4.0
6.
1 12.5 21.0 3.09 2.02 0.989
Polymer
Vinyl
chloride
1.41
6.73
62.0 94.2 186.2
1.
21
0.132 0.086 0.044
Sing
le
Si
2.42 6.44 60.6 93.3 189
0.738 0.079 0.
051
0.025
crystal
a-Si0
2
2.65 3.71 34.5 53.1 108 1.17 0.126
0.082 0.040
.
....
..
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