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The valence and core level spectra of chemically prepared, ideally H-terminated Si(l 11) surfaces are characterized by remarkably sharp features. The valence band levels and their dispersion are well described by first-principles calculations using a quasiparticle self-energy approach within the GW approximation. From the S'xip spectra, an upper limit of 35± 10 meV is derived for the core hole lifetime broadening, a value substantially lower than previously measured.

The surface reactivity of hydrogen-passivated, HF-cleaned Si(100) towards hydrocarbon adsorption is examined by surface analysis; most hydrocarbons adsorb on the surface. Dangling bonds formed during thermal processing react with fragmented organic molecules forming Sic, Metal-oxide-semiconductor devices fabricated on contaminated surfaces are degraded, with the degree of degradation depending on the nature of the contaminant.

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Angle-resolved photoemission spectroscopy (ARPES) measurements on copper using variable photon energy and attempting to derive E vs £ for the valence band have been already reported by different groups. 1 ' 3 However, in the previous attempts it was not possible to reach all the bands along the symmetry directions, because of either lack of high angular resolution 1 or the small photon energy range used. 2 * 3 In this Letter we report data obtained for photon energies of 15 < ftoo ^ 100 eV. This large energy range permits covering completely the direction TKX in normal emission and to observe all the bands (d and sp). Since photoemission involves both the initial and the final states, an analysis of such data requires an accurate model for the final-state bands. For this it is possible to use either an existing band 2 15 T. Schneider and E. Stoll, Phys. Rev. Lett. 41, 1429 (1978), and to be published. 16 In a recent paper by J. F. Currie, J. A. Krumhansl, A. R. Bishop, and S. E. Trullinger (to be published), it was shown that the {m p K) x^ coefficient arises from the phase-shift interaction of solitons with the harmonic models. It is possible to think that the extra power of | in Eq. (14) comes from the interaction of the solitons with the nonlinear magnons in the system. Vi Handbook of Mathematical Functions, edited by M. Abramowitz and I. A. Stegum (U. S. GPO, Washington, D.C., 1964), Ch. 20, Eq. 20.2.31.structure or a free-electron approach/ In the present work, we have found that the last one gives excellent results. The experimental valence band shows a very good agreement (± 100 meV) with the augmented-plane-wave (APW) calculation of Burdicko 4 In particular, the bottom of the sp band at T is in better agreement with these calculations than with the self-consistent bands of Janak, Williams, and Moruzzi. 5 ' 6 The measurement of the hole inverse lifetime at the bottom and the top of the d band gives values much smaller than recently reported. 2We present a very accurate determination of the valence bands of copper along TKX. This is obtained with high-resolution angle-resolved photoemission spectroscopy, using synchrotron radiation in the 15 ^fiio ^ 100 eV photon energy range. In addition the data yield inverse lifetime measurements for the 3d hole at the top and the bottom of the d band which have a value much smaller (< 50 and 250 meV) than recently reported. 82