Ulvac GI-M2 - Page 87

81
Table. 13-1 Relative Sensitivity Factor of Ion Gauge for Each Gas with Respect to Nitrogen
and Relative Ionization Cross-Sectional Area
m/e
N
Molecule
Srj
Xj
Srj:
Relatibe sensitibity of
ionization gauge
Srj(N
2
)=1(actual
measurment value
Xj:
Relative ionization cross-
sectional area
Xj(N
2
)=1
Calculated value when ion
electron energy is75 eV
N:
No. of electrons per
molecule
Linear relationship holds
between Sr and Xj and,
when Srj of the gas is
unknown, it can be
predicted from Xj
Values marked with [*] are
cited from Reference 2.
Unfortunately, data on
other types of gas are not
available at ULVAC
4
2
He
0.221*
0.13
±
0.02
20
10
Ne
0.358*
0.25
±
0.05
40
18
Ar
1.34*
1.23
±
0.07
84
36
Kr
1.88*
1.84
±
0.06
132
54
Xe
2.50*
2.64±0.08
2
2
H
2
0.491*
0.38
±
0.04
4
2
D
2
0.40
0.41
15
10
NH
3
0.645*
1.23
18
10
H
2
O
1.25
±
0.44
1.03
28
14
CO
0.95*
1.06
±
0.03
28
14
N
2
1.00
1.00
30
15
NO
1.17
±
0.11
1.24
32
16
O
2
0.879
0.96
±
0.07
Air
0.97
±
0.1
0.75
34
18
H
2
S
2.20
±
0.02
2.03
±
0.20
36
18
HCl
1.65
±
0.21
1.61
±
0.02
44
22
CO
2
1.35*
1.39
±
0.08
44
22
N
2
O
1.66
±
0.27
1.30
±
0.17
146
70
Sfe
2.50
2.41
200
80
Hg
3.30
±
1.04
2.07
±
0.04
16
10
CH
4
1.58*
1.63
±
0.30
30
18
C
2
H
6
2.58*
2.74
±
0.45
44
26
C
3
H
8
3.44*
3.64
±
0.37
58
34
C
4
H
10
4.04*
4.57
±
0.47
72
42
C
5
H
12
5.60
±
0.76
86
50
C
6
H
14
6.60
6.77
±
1.44
100
58
C
7
H
16
7.60
7.72
114
62
C
8
H
18
8.18
128
70
C
9
H
20
8.86
26
14
C
2
H
2
0.614*
2.06
±
0.27
28
16
C
2
H
4
1.29*
2.27
±
0.28
42
24
C
3
H
6
1.77*
3.25
±
0.22
56
32
C
4
H
8
2.07*
3.82
±
0.59
70
40
C
5
H
10
4.81
±
0.99
84
48
C
6
H
12
6.37
±
0.86
6.49
112
64
C
8
H
16
7.22
126
72
C
9
H
18
8.72
140
80
C
10
H
20
10.37
78
42
C
6
H
6
5.18
±
0.42
5.19
±
0.50
42
24
Cyclo-C
3
H
6
3.75
70
40
Cyclo-C
5
H
10
6.01
84
48
Cyclo-C
6
H
12
6.40
6.60
±
1.59
92
50
C
6
H
5
-CH
3
6.81
40
22
CH
2
-C-CH
2
1.31*
CH2=C=CH
2
40
22
CH
3
-C-CH
1.41*
CH3-C
≡
CH
1) F.Nakao.Vacuum25(1975)201,431
2) K.NakayamaandH.Hojo;Jpn.J.Appl.Phys.Suppl.2Pt.1.(1974)113