Development of a high-resolution soft x-ray (30-1500 eV) beamline at the advanced light source and its use for the study of angle-resolved photoemission extended fine structure

Bending magnet beamline 9.3.2 at the ALS was designed for high resolution spectroscopy with the capability for delivering circularly polarized light. The fixed included-angle SGM uses three gratings to access photon energies from 30-1500 eV. Circularly polarized radiation is obtained by inserting an aperture to select the beam above or below the horizontal plane. The photocurrent from the upper and lower jaws of the entrance slit sets a Piezoelectric drive feedback loop on the vertically deflecting mirror to maintain a stable beam intensity. The end station has a movable platform enabling the synchrotron radiation to be directed to either chamber without breaking vacuum.; With photoemission data collected at the Stanford Synchrotron Radiation Laboratory, the structure of c(2 x 2)P/Fe(100) was determined using angle-resolved photoemission extended fine structure (ARPEFS). The data were collected normal and 45{dollar}spcirc{dollar} off-normal from the (100) surface. Multiple-scattering spherical-wave (MSSW) calculations indicate that the P atoms adsorb in four-fold hollow sites 1.02 A above the first Fe layer. Self-consistent-field X{dollar}alpha{dollar} scattered wave calculation results agree with this c(2 x 2)P/Fe(100) and the previously published c(2 x 2)S/Fe(100) structures, confirming the ARPEFS determination that the Fe{dollar}sb1{dollar}-Fe{dollar}sb2{dollar} spacing is contracted for S/Fe but not for P/Fe. These structures are compared to atomic nitrogen and atomic oxygen adsorbed on Fe(100).; Final-state effects on ARPEFS curves were studied using previously published data from the S {dollar}1s{dollar} and {dollar}2p{dollar} core-levels of c(2 x 2)S/Ni(001). The curves are similar and {dollar}{lcub}sim{rcub}180spcirc{dollar} out of phase; the Fourier transforms (FTs) are quite different. A Generalized Ramsauer-Townsend splitting is present in the {dollar}1s{dollar} but not the {dollar}2p{dollar} data. Based on MSSW calculations, an approximate method for analyzing ARPEFS data from a non-s initial-state using only the higher-{dollar}ell{dollar} partial wave was proposed and successfully tested.; ARPEFS data from clean surfaces were collected normal to Ni(111) ({dollar}3p{dollar} core-levels) and {dollar}5spcirc{dollar} off-normal from Cu(111) ({dollar}3s{dollar} and {dollar}3p{dollar} core-levels). The two Cu curves are similar and {dollar}{lcub}sim{rcub}180spcirc{dollar} out of phase. The FTs of these ARPEFS data resemble adsorbate systems, showing backscattering signals from atoms up to four layers below the emitters. The {dollar}3p{dollar} FTs show scattering from the six nearest neighbors in the same crystal layer as the emitters. MSSW calculation results indicate that the Cu {dollar}3p{dollar} photoemission intensity has mostly d-wave character. Evidence was seen in the FTs for double-scattering and for single-scattering from laterally distant atoms. Calculations indicate that the signal is dominated by photoemission from the first two crystal layers.