The atomic structure of the Si(111) (2 root 3x2 root 3)R30 degrees-Sn reconstruction

We have studied the atomic structure of the (2 root 3x2 root)R30 degrees reconstruction induced by adsorption of about 1.1 monolayers of Sn on Si(lll) using surface X-ray diffraction (SXRD) and scanning tunnelling microscopy (STM). The experimentally obtained structure factors in SXRD are in contradiction with existing models in the literature and we conclude the need for a new surface atomic structure model. We have been able to determine a number of properties of an appropriate surface model to allow a better fit to the experimental structure factors.