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 191).

Diffusion of Hydrogen and Deuterium on the (111) Plane of Tungsten. C.Dharmadhikari, R.Gomer: Surface Science, 1984, 143[1], 223-42

Figure 41

Diffusivity of D and H on the (110) Plane of W

(circles: H, squares: D)