MICROSCOPIC OBSERVATION OF ATOMIC DISORDER NEAR THE ROUGHENING TRANSITION AT VICINAL COPPER SURFACES

The appearance of a reversible order-disorder transition at Cu(115) and Cu(117) surfaces has been investigated using perturbed angular correlation spectroscopy. The local atomic arrangement at In-111 probes is detected via nuclear quadrupole hyperfine interaction. A broadening of the electric field gradient distribution is measured for elevated temperatures due to structural changes around the probes. The onset of disorder on the atomic scale is found to be well above the roughening transition temperatures measured by various scattering techniques.