Franklin, GillianFontes, E.Qian, Y.Bedzyk, M. J.Golovchenko, JenePatel, J. R.2016-11-181994Franklin, G. E., E. Fontes, Y. Qian, M. J. Bedzyk, J. A. Golovchenko, and J. R. Patel. 1994. Thermal Vibration Amplitudes and Structure of As on Si(001). Physical Review B 50, no. 11: 7483–7487. doi:10.1103/physrevb.50.7483.0163-1829http://nrs.harvard.edu/urn-3:HUL.InstRepos:29407026Using the x-ray standing-wave method, we have measured directly the thermal vibration amplitudes 〈u2〉 of symmetric As dimers on a Si(001)-(2×1) surface. For sample temperatures in the range 300 K ≤T≤650 K, the results are Debye-like. Above 650 K 〈u2〉 varies more rapidly, indicating the onset of defect-mediated processes. We also found that at room temperature the bond length of the As dimers is 2.58±0.04 Å and that, independent of temperature, they sit 1.40±0.01 Å above the top bulk-extrapolated silicon (004) plane. These results provide a critical test for theoretical structure calculations.en-USJournal Article2016-11-1810.1103/PhysRevB.50.7483