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Chapter: 4 Atomic and nuclear physics
    Section: 4.4 Free electrons and ions in gases
        SubSection: 4.4.6 Electron collisions

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4.4.6 Electron collisions

Observed total collision cross-section of electrons with atoms and molecules

Q is the total collision cross-section in units of π α, where α0 is the radius of the first Bohr orbit of the hydrogen atom; α0 = 0.53 × 10−10 m. Hence the unit of Q in the tables below is 0.88 × 10−20 m2. The values are obtained by interpolation from graphs. General references: Landolt–Bornstein Tables (1950); Massey and Burhop (1952). For molecules, the data given relate to the Ramsauer method.

  Q in units of π α


Gas

(Energy)1/2/V1/2

0.5

1

1.5

2

3

4

5

6

7

8

9

10


H    .    .    .    .    .    .







6



7


.6


8


.6


9


.0


   —


   —


   —

H2  .    .    .    .    .    .

15

 

17

 

16

 

10

.5

7

 

5

.5

4

 

3

.5

   —

   —

   —

He  .    .    .    .    .    .

6

.3

6

.3

6

.2

5

.6

4

.6

3

.5

2

.6

2

.0

1

.7

1

.5

1

.3

1

.2

N2  .    .    .    .    .    .

17

 

10

 

29

 

13

 

12

 

12

.5

14

 

13

 

11

.5

O2  .    .    .    .    .    .

6

 

7

 

7

.5

8

 

11

 

12

 

12

 

12

 

CO .    .    .    .    .    .

15

 

14

 

38

 

18

 

14

 

14

 

14

 

Ne  .    .    .    .    .    .

1

.0

1

.9

2

.5

2

.8

3

.5

3

.7

3

.7

3

.6

3

.5

3

.4

3

.0

2

.9

Na  .    .    .    .    .    .

280

 

380

 

180

 

130

 

110

 

85

 

65

 

50

 

48

 

46

 

35

 

Ar  .    .    .    .    .    .

0

.6

0

.6

4

.0

8

.5

21

 

22

 

15

 

11

 

8

 

7

.5

7

 

6

.5

K   .    .    .    .    .    .

450

 

420

 

270

 

220

 

160

 

125

 

80

 

60

 

50

 

50

 

40

 

Zn  .    .    .    .    .    .

80

 

45

 

35

 

27

 

24

 

23

 

23

 

23

 

21

.5

Kr  .    .    .    .    .    .

2

.0

1

.0

6

.0

15

 

30

 

29

 

20

 

14

 

11

.5

9

 

8

 

7

.5

Rb  .    .    .    .    .

374

 

390

 

329

 

220

 

170

 

142

 

85

 

68

 

51

 

45

 

43

 

Cd  .    .    .    .    .    .

54

 

43

 

40

 

41

.5

39

 

34

 

31

 

29

 

Xe  .    .    .    .    .    .

7

.5

2

.0

15

 

33

 

43

 

32

.5

22

.5

16

 

Cs  .    .    .    .    .    .

470

 

675

 

350

 

300

 

230

 

160

 

135

 

100

 

80

 

67

 

46

 

Hg  .    .    .    .    .    .

80

 

70

 

55

 

23

 

18

 

18

 

20

 

20

 

18

.5

18

 

17

.5

Tl   .    .    .    .    .    .

6

 

10

 

16

 

12

.5

11

 

9

.5

9

.0

8

.8

8

.0

7

.0

6

.2

                                               


Cross-section (Q) for ionization by electron impact
Q is expressed in units of π α (i.e. 0.88 × 10−20 m2) for removal of the first electron

Gas
 
 

Energy/V

20

50

100

200

300

400

500

700

1000

2000

5000


H2    .    .    .    .    .    .    .    .    .


0.34


1.1


1.1


0.82


  0.68


  0.55


  0.45


  0.34


  0.25


0.12


0.06

He    .    .    .    .    .    .    .    .    .

0      

  0.28

  0.42

0.38

  0.31

  0.26

  0.22

  0.18

  0.14

0.08

0.04

N2    .    .    .    .    .    .    .    .    .

0.32

2.2

2.8

2.5    

2.2

1.9

1.6

1.3

1.0

0.51

0.23

O2    .    .    .    .    .    .    .    .    .

0.42

2.4

3.2

2.8   

2.5

2.1

1.9

1.5

1.2

0.60

0.30

CO   .    .    .    .    .    .    .    .    .

 

2.9

3.5

3.0   

2.4

2.0

1.8

 

 

 

 

NO   .    .    .    .    .    .    .    .    .

 

2.9

3.7

3.2   

2.7

2.5

2.0

 

 

 

 

Ne    .    .    .    .    .    .    .    .    .

0    

  0.41

  0.75

0.85

  0.77

  0.68

  0.60

  0.48

  0.38

0.23

0.11

Ar     .    .    .    .    .    .    .    .    .

0.75

3.2

3.3

2.5   

2.0

1.6

1.4

1.1

  0.88

0.48

0.23

Kr     .    .    .    .    .    .    .    .    .

1.4   

4.3

4.8

4.0   

3.2

2.8

2.5

1.9

1.5

0.85

0.34

Xe     .    .    .    .    .    .    .    .    .

4.0   

7.4

8.5

5.7   

4.6

4.0

3.4

2.8

2.3

1.5  

0.68

Hg    .    .    .    .    .    .    .    .    .

3.0   

5.8

6.3

5.5  

4.7

4.1

3.6

3.0

2.3

1.4  

0.68

 

 

 

 

 

 

 

 

 

 

 

 

      Data mainly from Tawara and Kato (1987).

J.W. Leake


References

S. F. Biagi (1989) Nuclear Instruments and Methods, A283, 716–722.
A. J. Blanc (1908) J. Physique, 7, 825.
L. G. Christophorou et al. (1979) Nuclear Instruments and Methods, 163, 141–149.
H. W. Ellis et al. (1976) Atomic Data and Nuclear Data Tables, 17, 177–210.
Ibid. Part II (1978) 22, 179–217.
Ibid. Part III (1984) 31, 113–151.
G. W. Fraser and E. Mathieson (1987) Nuclear Instruments and Methods in Physics Research, A257, 339–345.
R. H. Healey and J. W. Reed (1941) The Behaviour of Slow Electrons in Gases, Amalgamated Wireless Ltd,   
    Sydney.
L. G. H. Huxley et al. (1959) Australian Journal of Physics, 12, 303.
Landolt–Bornstein Tables (1950) Vol. I, Springer-Verlag.
L. B. Loeb (1955) Basic Processes of Gaseous Electronics, California University Press, 477 et seq.
E. W. McDaniel (1964) Collision Phenomena in Ionized Gases, Wiley, London.
H. S. W. Massey and E. H. S. Burhop (1952) Electronic and Ionic Impact Phenomena, Oxford University Press.
T. Nagy et al. (1960) Nuclear Instruments and Methods, 8, 327–330.
J. L. Pack, R. E. Voshall and A. V. Phelps (1962) Physical Review, 127, 2084–2089.
V. Palladino and B. Sadoulet (1975) Nuclear Instruments and Methods, 128, 323–335.
B. Schmidt and K. Martens (1992) Nuclear Instruments and Methods in Physics Research, A317, 148–154.
H. Tawara and T. Kato (1987) Atomic Data and Nuclear Data Tables, Academic Press, 36, 167–353.
A. M. Tyndall (1938) Mobility of Positive Ions in Gases, Cambridge University Press.
J. Va’vra (1992) Nuclear Instruments and Methods in Physics Research, A323, 34–47.

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