Surface charge density waves at Sn/Ge(111)?

We present a detailed high resolution photoemission investigation of the Sn/Ge(111) system which displays a reversible phase transition upon cooling from a √3×√3R(30°) to a 3 × 3 structure, just as Pb/Ge(111). The spectroscopic signatures are not in agreement with a surface charge density wave state at low temperature. We suggest instead that a rehybridization mechanism drives the transition.