By means of field-ion microscopy, it was found that the diffusion of single Ir adatoms on the 1 x 1 (110) surface was 2-dimensional. Thus, the adatom could diffuse along the [1¯10] surface channel by atomic hopping, as well as across the channel by atomic replacement:

cross-channel:     D (cm2/s) = 6.0 x 10-2 exp[-0.71(eV)/kT]

along-channel:     D (cm2/s) = 4.0 x 10-3 exp[-0.80(eV)/kT]

On the other hand, adatom diffusion on the 1 x 2 reconstructed surface, with doubly-spaced [1¯10] channels, was 1-dimensional and an adatom could hop only along these channels:

D (cm2/s) = 1.2 x 10-3 exp[-0.86(eV)/kT]

C.Chen, T.T.Tsong: Physical Review Letters, 1991, 66[12], 1610-3