It was recalled that strain was an important factor in the physics of surfaces, as shown by experiments on thin films and alloys. The effect of strain was studied by loading a cantilevered bar and by observing the resultant surface effects by means of low-energy electron diffraction and scanning tunnelling microscopy. On Si(100) surfaces, strain produced a reversible asymmetry in the relative populations of 2 x 1 and 1 x 2 domains. This required the motion of monatomic steps which were the domain boundaries. This process was driven by relaxation of the energy which was associated with a long-range strain field that extended into the bulk, due to an anisotropy of the intrinsic stress tensor of the 2 reconstructed domains. This was analogous to the manner in which magnetic domain structures reduced the magnetic field energy. These long-range strain fields had important consequences for a number of surface phenomena. Here, experiments on terrace width distributions were first reported. These furnished information concerning the effective step-step interactions. Experiments on the kinetics of step migration then furnished information on surface diffusion.

M.B.Webb, F.K.Men, B.S.Swartzentruber, R.Kariotis, M.G.Lagally: Surface Science, 1991, 242[1-3], 23-31