Tuesday, July 25, 2006, 1:30 am — Small Seminar Room, Bldg. 510
One possible way to prepare new complex structures is to offer a specific support to the material
(atoms and molecules) which will pronounce opportunistic forces for the self-organization of the
structures. The key in achieving this goal is in the preparation of well defined low-dimensional
structures. The system we investigate is Al2O3/Ni3Al(111). The specificity of this substrate is that the
ultra thin insulating layer (~ 5 Å) largely decouples interactions between adsorbates and the metallic
part of the substrate. The alumina film is characterized by a high degree of perfection due to its
commensurate structure with respect to Ni3Al(111), and consequently hundreds of nanometers large
domains. Previous room-temperature scanning tunneling microscopy (STM) studies have
shown that this surface can be used as a template to grow ordered hexagonal arrays of metal
clusters. The two apparent hexagonal “superstructures” of the alumina film (2.4 and 4.16 nm)
were directly accounted for the two typical periodicities found in the arraying. However, the
oxide film has a very complex structure which is not yet fully understood and its true atomic
structure is yet a puzzling challenge for both the experimental and theoretical surface science
community. The experimental data that we recently obtained by low-temperature STM and
spectroscopy show clear relation of distinct structural and electronic features of the alumina and the
so-far observed arraying. Also, we report on our recent investigations of possible arraying effects for
iron clusters and copper-phthalocyanine molecules.
Hosted by: Tonica Valla
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