By preventing surface alloying during growth of Sn on Cu(111) at 100 K, we discovered two novel nonalloying surface reconstructions, denoted as lower-coverage (LC) and higher-coverage (HC) phases. They were investigated with low energy electron diffraction (LEED), x-ray photoemission spectroscopy (XPS), and analysis of photoelectron extended fine structure (PEFS). The LC phase has a p(2 x 2) structure with one Sn atom per unit cell, corresponding to a Sn coverage 0.25 ML; the HC phase has a structure of M = ((2)(1) (1)(3)) (matrix notation) with two Sn atoms per unit cell, corresponding to a Sn coverage 0.40 ML. Structural models for the two phases are proposed.
