219
measurementsis estimated to be 4% orless for 10.85 <
E < 11.0 eV and £& > 11.4 eV, and 2% orless for other
photoionization cross sections, ¢:(¢; = na), are also
given in the tables.
ater
E values. The photoionization yield, , is the probability that photon absorption produces ionization. Tor
some gases the measured 7 values were pressure dependent in the energy region just below the ionization
potential,?: » and in these cases footnotes indicate the
pressures used. They values fora given EZ have a relative
uncertainty of approximately (2% of the 7 value) +
0.002, but the absolute (Z) values are more uncertain
because of the uncertainties in the 7(Z) values for acetone,” which was used as a secondary standard. The
“pelt
PPEPged 2 ENOa bibs wee
TABLE 80.
AssorPTion Cross SECTIONS, PHOTOIONIZATION YIELDS, AND PHOTOIONIZATION
Cross SECTIONS FOR ACETYLENE AND ACETYLENE-d,
lengthA
eV
1052.4
1055.6
1058.6
1061.7
1065.2
1069.9
1072.8
1076.8
1079.7
1081.6
1084.5
1088.7
1090.0
1092.4
1094.7
11.78
11.75
11.71
11.68
11.64
11.59
11.56
11.51
1148
11.46
11.43
11.39
11.37
11.35
11.33,
27.56
27.13
27.70
28.17
29.08
25.47
27.10
28.32
27.86
28.30
22.58
35.20
20.76
31.02
20.60
1.31
0.67
0.62
0.56
0.50
0.54
0.36
0.43
0.38
0.51
0.40
0.26
0.31
0.49
0.29
11.28
11.25
13.52
44.42
0.58
0.48
1098.1
11.29
1099.5
1102.0
- (a) 1 Mb
jen, Mb®) cx, Mb|
—_
22.71
1O- 18 em?.
(bh) Pressure ~(0.2 torr,
0.40
a
op, Mb
op, Mb
mp
10}
10
9
10
10
10
10
10
10
10
12
10)
12
10
12
27.15
27.21
27.98
(27.60
29.09
27.74
26.20
28.05
25.78
26.78
28.51
27.81
35.45
18.13
20.67
0.68
0.52
0.46
0.35
0.54
0.43
0.37
0.21
0.42
0.26
0.34
0.27
0.50
0.36
0.26
10
10
10
10
10
10
10
10
10
10
10
10
10
12
12
14
10
17.66
11.83
0.92
0.40
13
12
12
54.80
1.19
7
ms
ou ,Mb
o>, Mb
0.864
0.808
0.359
0.906
0.870
0.880
0.873
0.873
0.836
0.868
0.710
0.706
0.676
0.721
0.641
0.668
0.652
0.660
0.621
0.702
0.667
0.650
0.154| O.121|
0.040% ; 0.0200]
0.012
0.038
0.018
0.011
23. 80
23. 29
24.10
24.59
24.32
18.07
18.33
18.16
18.17
17.56
15.06
5.41|
o.g2)]
0.39
0.38
24.24
24.66
24.61
24.10
25. 25
19.59
18.90
18.75
17.03
18.81
18.52
3 agen
a4
0.69
0.23
0.001
0.000
0.02
0.02
0.08
0.05
0.002
™
0.002
0.005
0.004
0.05
0.09