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Title: High-resolution spectroscopy using synchrotron radiation for surface structure determination and the study of correlated electron systems

Abstract

The surface structure of three molecular adsorbate systems on transition metal surfaces, (√3 x √3)R30° and (1.5 x 1.5)R18° CO adsorbed on Cu(111), and c(2x2) N2/Ni(100), have been determined using Angle-Resolved Photoemission Extended Fine Structure (ARPEFS). The adsorption site and bond lengths are reported for the adsorbate-metal bond and the first two substrate layers. The ARPEFS diffraction pattern of the shake-up peak for c(2x2) N2/Ni(100) is also discussed. A unique method of experimentally determining the angular momentum and intrinsic/extrinsic origin of core-level satellites is presented. We show for the first time that satellite peaks not associated with chemically differentiated atomic species display an ARPEFS intensity oscillation. Specifically, we present data for the C 1s from (√3x√3)R30 CO/Cu(111) and p2mg(2x1)CO/Ni(110), N is from c(2x2) N2/Ni(100), and Ni 3p from clean nickel(111). The satellite peaks in all cases exhibit ARPEFS curves which indicate an angular momentum identical to the main peak and are of an intrinsic nature. A Fourier Transform Soft X-ray spectrometer (FF-SX) has been designed and is under construction for the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. The spectrometer is designed for ultra-high resolution theoretical resolving power E/ΔE≈-10 6 in the photon energy region of 60-120 eV.more » This instrument is expected to provide experimental results which sensitively test models of correlated electron processes in atomic and molecular physics. The design criteria and consequent technical challenges posed by the short wavelengths of x-rays and desired resolving power are discussed. The fundamental and practical aspects of soft x-ray interferometry are also explored.« less

Authors:
 [1]
  1. Univ. of California, Berkeley, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
285455
Report Number(s):
LBNL-38901; LSBL-330
ON: DE96014411; TRN: 96:005060
DOE Contract Number:
AC03-76SF00098
Resource Type:
Thesis/Dissertation
Resource Relation:
Other Information: TH: Thesis (Ph.D); PBD: May 1996
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; NICKEL; PHOTOELECTRON SPECTROSCOPY; COPPER; NITROGEN; X-RAY SPECTROMETERS; DESIGN; FOURIER TRANSFORM SPECTROMETERS; X-RAY SPECTROSCOPY; ADVANCED LIGHT SOURCE; ELECTRON DIFFRACTION

Citation Formats

Moler, Jr., Edward John. High-resolution spectroscopy using synchrotron radiation for surface structure determination and the study of correlated electron systems. United States: N. p., 1996. Web. doi:10.2172/285455.
Moler, Jr., Edward John. High-resolution spectroscopy using synchrotron radiation for surface structure determination and the study of correlated electron systems. United States. doi:10.2172/285455.
Moler, Jr., Edward John. 1996. "High-resolution spectroscopy using synchrotron radiation for surface structure determination and the study of correlated electron systems". United States. doi:10.2172/285455. https://www.osti.gov/servlets/purl/285455.
@article{osti_285455,
title = {High-resolution spectroscopy using synchrotron radiation for surface structure determination and the study of correlated electron systems},
author = {Moler, Jr., Edward John},
abstractNote = {The surface structure of three molecular adsorbate systems on transition metal surfaces, (√3 x √3)R30° and (1.5 x 1.5)R18° CO adsorbed on Cu(111), and c(2x2) N2/Ni(100), have been determined using Angle-Resolved Photoemission Extended Fine Structure (ARPEFS). The adsorption site and bond lengths are reported for the adsorbate-metal bond and the first two substrate layers. The ARPEFS diffraction pattern of the shake-up peak for c(2x2) N2/Ni(100) is also discussed. A unique method of experimentally determining the angular momentum and intrinsic/extrinsic origin of core-level satellites is presented. We show for the first time that satellite peaks not associated with chemically differentiated atomic species display an ARPEFS intensity oscillation. Specifically, we present data for the C 1s from (√3x√3)R30 CO/Cu(111) and p2mg(2x1)CO/Ni(110), N is from c(2x2) N2/Ni(100), and Ni 3p from clean nickel(111). The satellite peaks in all cases exhibit ARPEFS curves which indicate an angular momentum identical to the main peak and are of an intrinsic nature. A Fourier Transform Soft X-ray spectrometer (FF-SX) has been designed and is under construction for the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. The spectrometer is designed for ultra-high resolution theoretical resolving power E/ΔE≈-106 in the photon energy region of 60-120 eV. This instrument is expected to provide experimental results which sensitively test models of correlated electron processes in atomic and molecular physics. The design criteria and consequent technical challenges posed by the short wavelengths of x-rays and desired resolving power are discussed. The fundamental and practical aspects of soft x-ray interferometry are also explored.},
doi = {10.2172/285455},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1996,
month = 5
}

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  • Thesis submitted to University, Paris. The study of the hyperfine structure and isotope shift enabled the positions of the first five levels of the multiplet /sup 7/ F/sub 0-6/ belonging to the fundamental configuration /sup 5/f/ sup 6/7s/ sup 2/ to be determined. The classification of the arc spectrum begun in this way led to 25 odd levels, the number of classified lines (70) representing about 30 p. 100 of the light emitted by this hollow cathode in the visible. In addition, the isotope shifts of many lines and the data given by the King furnace show that the firstmore » levels of the configuration damental level /sup 7/Fo. The proximity of the configuration f/sup 6/s/sup 2/ and f/sup 5/ds/sup 2/ shows that the bonding energies of the 5f and 6d electrons are of the same order of magnitude and this fact must be responsible for the multiple valencies belonging to plutonium. From the hyperfine structure of spark lines (Pu II) the interval factor a/sub 7/ for the electron was deduced giving for the calculated nuclear moment of /sup 239/Pu a value of +0.21 plus or minus 0.06 mu N. The position of the hyperfine components show that the nuclear moment is positive, although the theoretical value given by B. R. Mottelson and S. Nillson is negative and equal to -0.1 mu /sub N/. (auth)« less
  • A high resolution Ge(Li) ..gamma..-ray spectroscopy detector for the on-line multielement monitoring of liquid chromatographic column effluents containing mixtures of ..gamma..-mixing radionuclides is described. Two spectra are collected simultaneously during the experiment - one to determine the individual ..gamma..-emitting components and one to determine the total radionuclide activities. The technique was successfully applied to the separation and determination of /sup 65/Ni(II), /sup 56/Mn(II), /sup 60/Co(II), /sup 64/Cu(II) by anion-exchange; acetylacetonate (acac) of /sup 51/Cr(III), /sup 60/Co(II), /sup 64/Cu(II), and /sup 56/Mn(II); and diethyldithiocarbamate, oxinate, and acetylacetonate of /sup 64/Cu(II) by silica gel adsorption chromatography. Advantages of this method over amore » uv detection method are discussed. Detection limits of /sup 51/Cr, /sup 69m/Zn, /sup 64/Cu, /sup 56/Mn, /sup 65/Ni, and /sup 60/Co separated on Dowex-1X8 were found to be 82, 11, 37, 25, 234, 35 nCi, respectively, at a flow rate of 1.0ml/min and for a cell volume of 75 ..mu..l. Detection limits of metal complexes separated on silica gel were found to be 2.85 x 10/sup -4/, 7.6 x 10/sup -5/, 8.3 x 10/sup -6/, 1.3 x 10/sup -5/ mmoles of Cr(acac)/sub 3/, Co(acac)/sub 3/, Cu(acac)/sub 2/, and Mn(acac)/sub 3/, respectively, at a flow rate of 2.0 ml/min and for a cell volume of 116 ..mu..l. (BLM)« less
  • Surface analytical equipment was developed to study gas reactions over single crystal surfaces. The equipment included LEED, AES, TDS, and a high resolution electron energy loss spectrometer (HREELS). This spectrometer is of the IBACH/SEXTON type, with two 127/sup 0/ electrostatic sectors and a matching pair of zoom lenses. The unit is capable of a resolution of 80 cm/sup -1/ (FWHM), at a primary energy of 5 eV and elastic counting rate of 10/sup 5/ Hz. In order to follow surface reactions in detail, a fast cooling manipulator was developed that allowed for cooling rates of the order of 10 K/sec.more » The techniques were used to study surface reactions over Pt(111). The first system studied was the formation of OH species through the reaction of co-adsorbed oxygen and water. It was found that at 100K, low oxygen coverages (O << 0.25), followed by exposing the surface to less than one monolayer of water resulted in the spontaneous formation of hydroxyl species. At high water exposures, in conjunction with careful thermal annealing, it was possible to observe the intermediate states in the evolution of the hydroxyl species. The second set of experiments were done on the adsorption and thermal annealing of methanol and (d-methanol) over clean Pt(111), an oxygen (atomic and molecular) pre-covered Pt(111), and a hydroxyl rich Pt(111).« less
  • In this thesis, both time-resolved, nonlinear optical spectroscopy and linear spectroscopy are used to investigate the interactions and dynamics of elementary excitations in strongly correlated electron systems. In the first part, we investigate the renormalization of magnetic elementary excitations in the transition metal oxide Cr 2O 3. We have created a non-equilibrium population of antiferromagnetic spin waves and characterized its dynamics, using frequency- and time-resolved optical spectroscopy of the exciton-magnon transition. We observed a time-dependent pump-probe line shape, which results from excitation induced renormalization of the spin wave band structure. We present a model that reproduces the basic characteristics ofmore » the data, in which we postulate the optical nonlinearity to be dominated by interactions with long-wavelength spin waves, and the dynamics due to spin wave thermalization. Using linear spectroscopy, coherent third-harmonic generation and pump-probe experiments, we measured the optical properties of the charge-transfer (CT) gap exciton in Sr 2CuO 2Cl 2, an undoped model compound for high-temperature superconductors. A model is developed which explains the pronounced temperature dependence and newly observed Urbach tail in the linear absorption spectrum by a strong, phonon-mediated coupling between the charge-transfer exciton and ligand field excitations of the Cu atoms. The third-order nonlinear optical susceptibility within the Cu-O plane of Sr 2CuO 2Cl 2 is fully characterized in both amplitude and phase, and symmetry based conclusions are made with respect to the spatial arrangement of the underlying charge distribution. Theoretical considerations ascribe a newly reported resonance in the third-order nonlinear susceptibility at 0.7 eV to a three-photon transition from the ground state to the charge-transfer exciton. An even parity intermediate state of Cudd character, is found to contribute to the transition. Finally, preliminary results of time-resolved pump-probe spectroscopy confirm that the CT exciton or one of its constituent parts couples strongly to phonons, and we suggest ultrafast thermalization with the lattice as the dominating mechanism underlying the dynamical properties.« less
  • The time dependence of the fluorescence from molecular states of krypton and xenon is measured following pulsed excitation of dense pure gas samples or binary gas mixtures by a low intensity beam of high energy electrons or by monochromatized vacuum ultraviolet (vuv) synchrotron radiation. The selectivity of the initial states excited by monochromatic photons is a significant advantage over electron beam excitation for the determination of radiative lifetimes and rates for reactions involving the lowest 1/sub u/ and 0/sub u//sup +/ states of krypton and xenon. Electron beam excitation remains valuable for study of excited states which cannot be reachedmore » by photoexcitation, particularly the ionic states of the rare gases. High vibrational levels of the lowest 1/sub u/ and 0/sub u//sup +/ molecular states can be produced directly by photoexcitaion. The vibrational relaxation to the lowest vibrational levels is complete within only a few collisions in the pure rare gases, with rate constants almost as large as gas kinetic collision rates. On the other hand, the rate constants for relaxation of the 0/sub u//sup +/ state of xenon by collisions with an argon atom is more than an order of magnitude small than in pure xenon. The lowest vibrational levels of the 1/sub u/ and 0/sub u//sup +/ states radiate in the vuv with radiative lifetimes determined to be 3.4 +- 3 nsec (0/sub u//sup +/) and 264 +- 5 nsec (1/sub u/) for krypton, and 4.6 +-.3 nsec (0/sub u//sup +/) and 99 +- 2 nsec (1/sub u/) for xenon. Transitions between these states induced by collisions with ground state atoms occur with very small reaction rate constants.« less