. In this study, the STM was used to locally study the adsorption of NO on a Rh(111) single crystal. Three new structures were identified. At 200 K, patches of the (4 × 2)-2NO and an unreported (2 × 2)-2NO structure were found at about 0.50ML coverage. Higher exposure gave rise to a (2 × 2)-3NO structure with all molecules adsorbed in the hcp sites. At 5K, a (4 × 4)-1NO structure was observed. The large separation between the molecules can only arise from repulsive interactions over a distance of at least four times the lattice constant (11 Å). Here the interaction is estimated to be of the order of ~10K or ~0.1 kJ/mol. Dynamic Monte Carlo simulations taking into account adsorption, diffusion and pairwise interactions between adsorbates were used to fit the lateral interaction for the next-next nearest neighbor to the patched STM topograph at 200K for 0.50ML coverage. The value was determined to be 2 kJ/mol. Using pairwise interactions only, the (2 × 2)-3NO structure could not be explained. It might therefore be necessary to include three-particle interactions. Recent DFT calculations support this idea by showing attractive three-particle interactions.
|Title of host publication||Proceedings of the International Conference on Nanoscience and Technology (ICN&T 2006), 30 July - 4 August 2006, Basel, Switzerland|
|Editors||E. Meijer, M. Hegner, H.-J. Güntherodt|
|Place of Publication||Bristol|
|Publisher||Institute of Physics|
|Publication status||Published - 2007|
|Name||Journal of Physics: Conference Series|