
VOLUME 33 (1981)  ISSUE 6 
PAGE 343

Diffusion in twodimensional crystals
Lyuksyutov I. F., Pokrovskii V. L.
In experiments on the diffusion of a submonolayer barium film on the Mo(l 10) face, Vedula et al.^{l}'^{2} found that the diffusion coefficient D, the activation energy e_{a}, and the coefficient (D_{0}) of the exponential function are all nonmonotonic functions of the degree of surface coverage θ (the ratio of the actual concentration of adatoms to the concentration in a closely packed monolayer). Earlier studies of structures in this system^{3} had demonstrated the existence of several commensurable phases at small values of Θ and of an incommensurable phase at θ >0.6. Comparison of structural data with data on diffusion reveals a correlation. In particular, e_{a} and Do have minima at coverages corresponding to the phases C(2 X 6) (0 = 0.8) and C(2 X 2) (0 = 0.6). The activation energy near these minima has clearly defined plateaus in an interval Δ0 ~ 0.1, while D_{0} increases by a factor of 10^{3} 10^{s} in an interval^{1}* Δ0~Ο.1.

