The presence of an interface in a liquid invariably changes the structure of the near-interface region. Modern purpose-designed beamlines at advanced synchrotron sources allow determining this structure with sub-atomic resolution not only for free surfaces but also for deeply-buried interfaces between the liquid and a solid or another, immiscible, liquid. For liquid metals and alloys, starting with the first observation of surface-induced layering in mercury and gallium in 1995[1], such measurements have revealed many intriguing surface-induced ordering effects at free surfaces, like atomic layering in pure metals[1], anomalous capillarity[1], wetting and adsorption phenomena in binary metal alloys[2], surface-induced crystalline monolayer formation in metal-semiconductor alloys[3], and more. Following a short introduction to the techniques used, results obtained for the free surface of liquid metals and alloys will be presented. These will be followed by results for deeply-buried interfaces, obtained using recently-opened microfocus high-energy beamlines. These results include unexpected modifications to the interfacial layering at the solid interface[4], and the interfacial structure of a liquid metal/electrolyte interface under an applied voltage[5], exhibiting anomalous temperature and voltage dependences. Results from ongoing research involving liquid metals will also be presented.
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[2] P. Huber, O. Shpyrko, P.S. Pershan, B.M. Ocko, H. Tostmann, E. DiMasi, M. Deutsch, Phys. Rev. Lett. 89, 035502 (2002).
[3] O.G. Shpyrko, R. Streitel, V.S.K. Balagurusamy, A.Y. Grigoriev, M. Deutsch, B.M. Ocko, M. Meron, B.H. Lin, P.S. Pershan, Science 313, 77 (2006); S. Mechler, S.E. Stoltz, P.S. Pershan, E. Yahel, O.G. Shpyrko, B.H. Lin, M. Meron, S. Sellner, Phys. Rev. Lett. 105, 186101(2010).
[4] L. Tamam, D. Pontoni, T. Hofmann, B.M. Ocko, H. Reichert, M. Deutsch, J. Phys. Chem. Lett. 1, 1041 (2010).
[5] A. Elsen, B.M. Murphy, B.M. Ocko, L. Tamam, M. Deutsch, I. Kuzmenko, and O.M. Magnussen, Phys. Rev. Lett. 104, 105501 (2010).