The migration of 1H and 2H on the (111) plane of a W field emitter was studied by using the fluctuation method. Both activated and unactivated diffusion was observed. As the latter revealed a very small isotope effect, it was suggested that mass renormalization caused the effective masses of 1H and 2H to be essentially identical. The diffusivity values in the temperature-independent regime ranged from 5 x 10-14 to 10-13cm2/s; depending upon the coverage (table 328).

C.Dharmadhikari, R.Gomer: Surface Science, 1984, 143[1], 223-42

 

Table 328

Diffusion of D and H on the (001) Plane of W

at Temperatures of between 78 and 200K

 

System

Coverage

Regime

Do (cm2/s)

Q (kcal/mol)

1H[010]

0.06

fast

6.8 x 10-10

1.5

1H[010]

0.06

slow

1.0 x 10-10

1.6

1H[010]

0.3

fast

5.2 x 10-10

2.2

continued

 

Table 328 (continued)

Diffusion of D and H on the (001) Plane of W

at Temperatures of between 78 and 200K

 

System

Coverage

Regime

Do (cm2/s)

Q (kcal/mol)

1H[010]

0.06

fast

6.8 x 10-10

1.5

1H[010]

0.06

slow

1.0 x 10-10

1.6

1H[010]

0.3

fast

5.2 x 10-10

2.2

1H[010]

0.3

slow

1.4 x 10-10

2.4

1H[010]

0.6

fast

4.0 x 10-10

2.0

1H[010]

0.6

slow

1.7 x 10-10

2.1

1H[010]

0.9

fast

2.4 x 10-9

2.6

1H[010]

0.9

slow

8.3 x 10-10

2.7

1H[100]

0.06

fast

5.8 x 10-10

1.9

1H[100]

0.06

slow

1.9 x 10-10

2.0

1H[100]

0.3

fast

3.2 x 10-11

1.3

1H[100]

0.3

slow

1.7 x 10-11

1.5

1H[100]

0.6

fast

1.7 x 10-10

1.7

1H[100]

0.6

slow

5.3 x 10-11

1.7

1H[100]

0.9

fast

2.0 x 10-9

2.4

1H[100]

0.9

slow

8.2 x 10-10

2.4

2H[010]

0.06

fast

8.4 x 10-11

1.2

2H[010]

0.06

slow

3.4 x 10-11

1.3

2H[010]

0.3

fast

8.2 x 10-10

2.4

2H[010]

0.3

slow

3.6 x 10-10

2.5

2H[010]

0.6

fast

6.1 x 10-11

1.6

2H[010]

0.6

slow

2.1 x 10-11

1.7

1H[100]

0.6

slow

5.3 x 10-11

1.7

1H[100]

0.9

fast

2.0 x 10-9

2.4

1H[100]

0.9

slow

8.2 x 10-10

2.4

2H[010]

0.06

fast

8.4 x 10-11

1.2

2H[010]

0.06

slow

3.4 x 10-11

1.3

continued

Table 328 (continued)

Diffusion of D and H on the (001) Plane of W

at Temperatures of between 78 and 200K

 

System

Coverage

Regime

Do (cm2/s)

Q (kcal/mol)

2H[010]

0.3

fast

8.2 x 10-10

2.4

2H[010]

0.3

slow

3.6 x 10-10

2.5

2H[010]

0.6

fast

6.1 x 10-11

1.6

2H[010]

0.6

slow

2.1 x 10-11

1.7

1H[100]

0.6

slow

5.3 x 10-11

1.7

1H[100]

0.9

fast

2.0 x 10-9

2.4

1H[100]

0.9

slow

8.2 x 10-10

2.4

2H[010]

0.06

fast

8.4 x 10-11

1.2

2H[010]

0.06

slow

3.4 x 10-11

1.3

2H[010]

0.3

fast

8.2 x 10-10

2.4

2H[010]

0.3

slow

3.6 x 10-10

2.5

2H[010]

0.6

fast

6.1 x 10-11

1.6

2H[010]

0.6

slow

2.1 x 10-11

1.7

2H[010]

0.9

fast

5.2 x 10-11

1.5

2H[010]

0.9

slow

1.2 x 10-11

1.4

2H[100]

0.06

fast

3.0 x 10-9

2.4

2H[100]

0.06

slow

3.4 x 10-10

2.3

2H[100]

0.3

fast

4.4 x 10-10

2.2

2H[100]

0.3

slow

3.9 x 10-11

1.9

2H[100]

0.6

fast

2.1 x 10-10

1.9

2H[100]

0.6

slow

3.4 x 10-11

1.8

2H[100]

0.9

fast

8.1 x 10-10

2.4

2H[100]

0.9

slow

1.2 x 10-10

2.3