skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: High-resolution electron-energy-loss spectroscopy and photoelectron-diffraction studies of the geometric structure of adsorbates on single-crystal metal surfaces

Abstract

Two techniques which have made important contributions to the understanding of surface phenomena are high resolution electron energy loss spectroscopy (EELS) and photoelectron diffraction (PD). EELS is capable of directly measuring the vibrational modes of clean and adsorbate covered metal surfaces. In this work, the design, construction, and performance of a new EELS spectrometer are described. These results are discussed in terms of possible structures of the O-Cu(001) system. Recommendations for improvements in this EELS spectrometer and guidelines for future spectrometers are given. PD experiments provide accurate quantitative information about the geometry of atoms and molecules adsorbed on metal surfaces. The technique has advantages when used to study disordered overlayers, molecular overlayers, multiple site systems, and adsorbates which are weak electron scatterers. Four experiments were carried out which exploit these advantages.

Authors:
Publication Date:
Research Org.:
Lawrence Berkeley Lab., CA (USA); California Univ., Berkeley (USA). Dept. of Chemistry
OSTI Identifier:
6950660
Report Number(s):
LBL-14774
ON: DE83003395
DOE Contract Number:
AC03-76SF00098
Resource Type:
Technical Report
Resource Relation:
Other Information: Thesis. Submitted to the Univ. of California, Berkeley, CA
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 47 OTHER INSTRUMENTATION; COPPER; ELECTRON SPECTROSCOPY; PHOTOELECTRON SPECTROSCOPY; SURFACE PROPERTIES; ELECTRON SPECTROMETERS; PERFORMANCE; NICKEL; ADSORPTION; ELECTRON COLLISIONS; ELECTRON DIFFRACTION; ELECTRON PROBES; ELECTRONIC STRUCTURE; EXPERIMENTAL DATA; MONOCRYSTALS; OXYGEN; RESOLUTION; SPECIFICATIONS; VIBRATIONAL STATES; COHERENT SCATTERING; COLLISIONS; CRYSTALS; DATA; DIFFRACTION; ELEMENTS; ENERGY LEVELS; EXCITED STATES; INFORMATION; MEASURING INSTRUMENTS; METALS; NONMETALS; NUMERICAL DATA; PROBES; SCATTERING; SORPTION; SPECTROMETERS; SPECTROSCOPY; TRANSITION ELEMENTS; 360102* - Metals & Alloys- Structure & Phase Studies; 640301 - Atomic, Molecular & Chemical Physics- Beams & their Reactions; 440300 - Miscellaneous Instruments- (-1989)

Citation Formats

Rosenblatt, D.H. High-resolution electron-energy-loss spectroscopy and photoelectron-diffraction studies of the geometric structure of adsorbates on single-crystal metal surfaces. United States: N. p., 1982. Web. doi:10.2172/6950660.
Copy to clipboard
Rosenblatt, D.H. High-resolution electron-energy-loss spectroscopy and photoelectron-diffraction studies of the geometric structure of adsorbates on single-crystal metal surfaces. United States. doi:10.2172/6950660.
Copy to clipboard
Rosenblatt, D.H. Mon . "High-resolution electron-energy-loss spectroscopy and photoelectron-diffraction studies of the geometric structure of adsorbates on single-crystal metal surfaces". United States. doi:10.2172/6950660. https://www.osti.gov/servlets/purl/6950660.
Copy to clipboard
@article{osti_6950660,
title = {High-resolution electron-energy-loss spectroscopy and photoelectron-diffraction studies of the geometric structure of adsorbates on single-crystal metal surfaces},
author = {Rosenblatt, D.H.},
abstractNote = {Two techniques which have made important contributions to the understanding of surface phenomena are high resolution electron energy loss spectroscopy (EELS) and photoelectron diffraction (PD). EELS is capable of directly measuring the vibrational modes of clean and adsorbate covered metal surfaces. In this work, the design, construction, and performance of a new EELS spectrometer are described. These results are discussed in terms of possible structures of the O-Cu(001) system. Recommendations for improvements in this EELS spectrometer and guidelines for future spectrometers are given. PD experiments provide accurate quantitative information about the geometry of atoms and molecules adsorbed on metal surfaces. The technique has advantages when used to study disordered overlayers, molecular overlayers, multiple site systems, and adsorbates which are weak electron scatterers. Four experiments were carried out which exploit these advantages.},
doi = {10.2172/6950660},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Nov 01 00:00:00 EST 1982},
month = {Mon Nov 01 00:00:00 EST 1982}
}
Copy to clipboard
Technical Report:
View Technical Report (1.97 MB)
DOI:  10.2172/6950660
Save / Share:
Export Metadata
Save to My Library
You must Sign In or Create an Account in order to save documents to your library.

  • ; ;
    This paper discusses the structures of adsorbed CO, several olefins, and several other small molecules that were recently studied by both LEED and HREELS studies. When adsorbed on metal-crystal surfaces, several binding states of CO have been observed that fill as a function of coverage. Acetylene, ethylene, propylene, methylacetylene, and butenes all undergo structural transitions as a function of temperature and are accompanied by drastic changes in bonding. On Pt and Rh single-crystal surfaces, the most-stable molecular arrangement for these adsorbed hydrocarbons near room temperature appears to be the alkylidyne structure with the C-C bond axis perpendicular to the metalmore » surface and the molecule anchored to a 3-fold surface site on a (111) plane. Increased temperatures lead to sequential bond breaking and fragmentation. The CH and C/sub 2/H fragments appear to be the active species present on transition-metal surfaces during catalytic reactions. The vibrational spectra obtained on single-crystal and dispersed rhodium particle surface are also compared.« less

  • ; - J. Phys. Chem.; (United States)
    The chemisorption and thermal decomposition of acetylene and ethylene on Ni(100) surfaces were studied by using thermal programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS). Acetylene chemisorbs molecularly at 90 K forming a rehybridized (sp/sup 3/) acetylenic moiety on the surface. This fragment is stable up to 270 K, where dehydrogenation takes place to form CCH residues. Heating further, above 400 K, leaves only carbon on the nickel surface. Ethylene also adsorbs molecularly but with little rehybridization, H bonding to the metal. Stepwise dehydrogenation takes place as the crystal temperature is increased. Vinyl is formed as a productmore » of a unimolecular reaction at 170 K for low coverages of ethylene (theta less than or equal to 0.4), but this process is inhibited at higher coverages and only takes place around 200 K. A strong isotope effect was also observed, and C/sub 2/D/sub 4/ decomposition only occurred at temperatures about 40 K higher. Vinyl decomposes further to form an acetylenic moiety at about 230 K. Further heating is followed by stepwise dehydrogenation similar to that observed when acetylene is adsorbed. No H-D scrambling is observed during the thermal treatment for partially or fully deuterated molecules.« less

  • ; - Phys. Rev., B; (United States)
    Low-energy-electron diffraction, Auger-electron spectroscopy, electron-energy-loss, and ultraviolet-photoelectron spectroscopies were used to study the structure, composition, and electron energy distribution of a clean single-crystal (111) face of strontium titanate (perovskite). The dependence of the surface chemical composition on the temperature has been observed along with corresponding changes in the surface electronic properties. High-temperature Ar-ion bombardment causes an irreversible change in the surface structure, stoichiometry, and electron energy distribution. In contrast to the TiO/sub 2/ surface, there are always significant concentrations of Ti/sup 3 +/ in an annealed ordered SrTiO/sub 3/ (111) surface. This stable active Ti/sup 3 +/ monolayer on topmore » of a substrate with large surface dipole potential makes SrTiO/sub 3/ superior to TiO/sub 2/ when used as a photoanode in the photoelectrochemical cell.« less

  • Adsorption studies have been carried out on single crystal surfaces of Ni and Cr using EELS, low energy electron diffraction, and Auger electron spectroscopy. H/sub 2/S adsorption has been studied on Ni(100) at temperatures between 110 and 295/sup 0/K. Adsorbed CH/sub 3/NH/sub 2/ has been studied on Ni(100), Ni(111), Cr(100), and Cr(111) at 300/sup 0/K. Dissociative chemisorption of O/sub 2/ and CO has been characterized on Cr(100), Cr(110), and Cr(111). Based on a sequence of O/sub 2/ exposures at 300/sup 0/K and after 625/sup 0/K and 1175/sup 0/K anneals, a model of the initial oxidation of Cr(100) is proposed. Subsurfacemore » oxygen in interstitial sites with Cr atoms maintaining bulk positions is proposed to act as a nucleus for subsequent oxide growth. Oxide growth at 300/sup 0/K is proposed to occur primarily through domain expansion, while frequent creation of new domains is observed at 625/sup 0/K. At elevated temperatures competition between domain growth and diffusion into the bulk is observed.« less

  • ; - ACS Symposium Series
    The scattering of low energy electrons by metal surfaces has been studied for many years now. The electron's ease of generation and detection and high surface sensitivity (low penetration depth) make it an ideal probe for surface scientists. The impinging electron can interact with the surface in basically two ways: it can either elastically reflect (or diffract) from the surface without losing energy or lose a portion of it's incident energy and inelastically scatter. In this paper we will be concerned with only one of many possible inelastic scattering processes: the loss of the electron's energy to the vibrational modesmore » of atoms and molecules chemisorbed on the surface. This technique is known as high resolution electron energy loss spectroscopy (or ELS, EELS, HRELS, HREELS, etc.).« less