Surface oxidation of liquid Sn

Wereport the results of anX-ray scattering study that reveals oxidation kinetics and formation of a previously unreported crystalline phase of SnO at the liquid–vapour interface of Sn. Our experiments reveal that the pure liquid Sn surface does not react with molecular oxygen below an activation pressure of 5.0 · 10 Torr. Above that pressure a rough solid Sn oxide growsover the liquidmetal surface.Once the activation pressure has been exceeded the oxidationproceeds at pressures below the oxidation pressure threshold. The observed diffraction pattern associated with the surface oxidation does not match any of the known Sn oxide phases. The data have an explicit signature of the face-centred cubic structure, however it requires lattice parameters that are about 9% smaller than those reported for cubic structures of high-pressure phases of Sn oxides. 2004 Elsevier B.V. All rights reserved.