ABSTRACT
Transport coefficients 01-1000 Yousfi and Benabdessadok (1996)
Differential scattering 2-30 Alle et al. (1992) Vibrational excitation 5, 75, 15 Gulley et al. (1992) Ionization cross section 15-1000 Rao and Srivastava (1992) Ionization cross section 10-270 Syage (1992) Total scattering cross section
75-4000 Zecca et al. (1992)
Total scattering cross section
1-100 Szmytkowski et al. (1989)
Total scattering cross section
1-400 Sueoka et al. (1987)
Drift velocity (1-10) Christophorou et al. (1982) Ionization coefficients (30-3000) Risbud and Naidu (1979) Attachment coefficients (60-120) Risbud and Naidu (1979) Attachment coefficients (45-90) Parr and Moruzzi (1972) Attachment cross section 4-135 Sharp and Dowell (1969) Drift velocity (001-20) Pack et al. (1962) Attachment coefficients (45-60) Bradbury (1934) Attachment coefficients (45-90) Bailey and Duncanson
(1930)
Note:Bold font indicates experimental study
Figure 391 The highlights are
1 A trend of increasing cross section toward lower energy below 1 eV
2 A shallow Ramsauer-Townsend minimum at ~25 eV 3 A broad shape resonance at ~10 eV attributed to the
temporary attachment of electron 4 For energy >10 eV, the cross section decreases
approximately according to ε−1/2
Figure 392 shows the differential scattering cross sections for NH3 (Boesten et al, 1996) The highlights are
1 A steep decline in differential cross section as the angle increases, signifying forward scatteringThis behavior is attributed to the dipole moment of the molecule, though molecules having a smaller dipole moment, such as (N2O, 0167 D), also demonstrate the same behavior
2 The forward scattering is observed at all energies in the range 2-30 eV
TABLE 39.3 Total Scattering Cross Sections for NH3 Energy (eV)
QT (10-20 m2)
Energy (eV)
QT (10-20 m2)
Energy (eV)
QT (10-20 m2)
Itikawa (2003) Zecca et al. (1992) Sueoka et al. (1987)
10 145 75 100 10 147
12 133 80 963 12 134
15 120 90 907 14 124
17 114 100 854 16 116
20 108 110 787 18 111
25 105 125 737 20 109
30 107 150 686 22 104
35 114 175 618 25 101
40 126 200 564 28 108
45 140 225 511 31 112
50 156 250 481 34 113
60 180 300 425 37 113
70 203 350 386 40 120
80 219 400 347 45 134
90 228 450 315 50 145
10 229 500 294 55 152
12 218 600 251 60 155
15 201 700 220 65 157
17 191 800 199 70 169
20 178 900 178 75 175
25 161 1000 161 80 171
30 148 1100 147 85 171
35 138 1250 131 90 175
40 130 1500 110 95 175
45 123 1750 0939 100 175
50 118 2000 0854 110 175
60 109 2250 0757 120 169
70 103 2500 068 130 169
80 968 2750 0622 140 164
90 910 3000 0554 150 160
100 857 3250 0505 160 155
120 764 3500 0466 170 150
150 667 4000 0413 180 149
170 617 190 145
200 555 200 142
250 476 220 140
300 4421 250 129
350 375 300 121
400 338 350 110
Cross Sections for NH3 Energy (eV)
QT (10-20 m2)
Energy (eV)
QT (10-20 m2)
Energy (eV)
QT (10-20 m2)
Itikawa (2003) Zecca et al. (1992) Sueoka et al. (1987)
450 313 400 105
500 288 500 93
600 250 600 88
700 221 700 83
800 199 800 79
900 181 900 73
1000 166 100 70
120 63
150 56
200 50
250 42
300 39
350 35
400 32
Source: Adapted from ItikawaY, (Ed), Interactions of Photons and Electrons with Molecules, Vol 17c, Landolt-Börnstein, Springer, 2003
Pack et al (1962) have derived the momentum transfer cross section at very low energies (01 ≤ ε ≤ 10 eV) according to
1 4 93 10 1 51 1017 1 2 19 3 2 2
QM = × + × −. ./ /ε ε m
(391)
Table 394 shows the integral elastic and momentum transfer cross sections for NH3 (Alle et al, 1992) Figure 393 shows the cross sections (Boesten et al, 1996)
A single value of vibrational excitation cross section for (ν1 + ν3) mode of 067 × 10−20 m2 at 75 eV has been reported by Gulley et al (1992)
Table 395 shows the ion appearance potentials for NH3 (Mann et al, 1940)
3.92 Cross section
Ammonia (NH3)
Ang le(°)En
erg y(e
V)
120°eV 2
15 30
TABLE 39.4 Integral Elastic and Momentum Transfer Cross Sections
Energy (eV) Qel (10-20 m2) QM (10-20 m2)
2 1122 224
5 1583 875
75 1621 915
15 1616 1006
20 1443 640
30 1097 573
2 1 10
Alle QM
(QT) Qel
Alle NH3
Sueoka
theory
Electron energy (eV) 100
TABLE 39.5 Ion Appearance Potentials
Ion Energy (eV) Probable Process Description
NH3 + 105 NH3 + e → NH3+ Ionization
NH2 + 157 NH3 + e → NH2+ + H Dissociative ionization
NH+ 194 NH3 + e → NH+ + H2 Dissociative ionization 237 NH3 + e → NH+ + 2H Dissociative ionization
N+ 249 NH3 + e → N+ + 3H Dissociative ionization 280 NH3 + e → N+* + 3H Dissociative ionization
H+ 233 NH3 + e → NH + H + H+ Dissociative ionization 269 NH3 + e → N* + 2H + H+ Dissociative ionization
H2 + 155 H2 → H2+ Dissociative ionization
NH3 + e → NH + H2+ Dissociative ionization NH32+ 42 NH3 + e → NH32+ Double ionization H− 376 NH3 + e →NH2 + H− Dissociative
attachmenta
503 NH3 + e →NH2* + H− Dissociative attachmenta
58 NH3 + e → N + H2+H− Dissociative attachment
230 NH3 + e → NH+ + H + H− Ion pair production NH2
− 330 NH3 + e → H + NH2− Dissociative attachmenta
578 NH3 + e → H + NH2 −* Dissociative
attachmenta
60 NH3 + e → H + NH2− Dissociative attachment
1350 NH3 + e → H* + NH2− Dissociative attachmenta
aData are from Sharp and Dowell (1969)
Table 396 and Figures 394 and 395 show the ionization cross sections for NH3 Figure 394 shows the partial ionization cross sections from Rejoub et al (2001)
Attachment cross sections measured by Sharp and Dowell (1969) have been renormalized by Itikawa (2003) as shown in Table 397 and Figure 396
Total Ionization Cross SNH3
Qi (10-20 m2)
Energy (eV) Rejoub et al.
