Synchrotron radiation photoemission studies of core level excitation effects

Conference · Mon Jan 01 04:00:00 EST 1979

OSTI ID:6066969

Williams, G P; Lapeyre, G J; Anderson, J; Cerrina, F; Dietz, R E; Yafet, Y

The recent availability of intense polarized radiation tunable over the range 20-150 eV enables several core levels to be excited. Several remarkable effects have recently been reported when core excitation thresholds have been reached. For example, an increase in yield of 50% was observed in GaSe at the Se 3d threshold (h omega approx. = 57 eV). A considerable increase in photoemission intensity at 6 eV binding energy has been reported by Guillot et al. for Ni at the 3p threshold. A very careful study was made using the CIS, CFS, and EDC modes of photoemission spectroscopy of core threshold effects in Ni, Pt, and GaSe. A modulation of the Ni Fermi edge emission as a function of photon energy is found which is attributed to a configuration interaction between 3p/sup 5/3d/sup 10/4s and 3p/sup 6/3d/sup 8/4s epsilon f. Similar effects occur in Pt at the 4f threshold involving the configurations 4f/sup 13/5d/sup 10/6s and 4f/sup 14/5d/sup 8/6s. Further, the lineshapes of the Pt and Ni upper valence band CIS's resemble those obtained by electron energy loss (ELS) and photoabsorption, all of which can be fitted theoretically to a Fano model. Emission from levels lying well below the Fermi level often has superimposed contributions due to incoherent effects which complicate the interpretation. In cases in which core levels are excited well above threshold, the CIS technique may be used to examinefinal states. Of particular interest is the possible consequent determination of adsorbate site geometry. Data are presented for 2p emission from a c(2x2) Na overlayer on Ni (001).

• Research Organization: Brookhaven National Lab., Upton, NY (USA); Montana State Univ., Bozeman (USA). Dept. of Physics; Bell Labs., Murray Hill, NJ (USA)
• DOE Contract Number: EY-76-C-02-0016
• OSTI ID: 6066969
• Report Number(s): BNL-25912; CONF-790356-1
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
360603 -- Materials-- Properties
BAND THEORY
BEAMS
BINDING ENERGY
BREMSSTRAHLUNG
CHALCOGENIDES
CONFIGURATION INTERACTION
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DATA
DATA FORMS
ELECTROMAGNETIC RADIATION
ELECTRON SPECTROSCOPY
ELECTRONIC STRUCTURE
ELEMENTS
EMISSION
ENERGY
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXPERIMENTAL DATA
FERMI LEVEL
GALLIUM COMPOUNDS
GALLIUM SELENIDES
GRAPHS
INCOHERENT SCATTERING
INFORMATION
METALS
MODULATION
NICKEL
NUMERICAL DATA
PHOTOELECTRON SPECTROSCOPY
PHOTOEMISSION
PLATINUM
PLATINUM METALS
POLARIZED BEAMS
RADIATIONS
RESONANCE
SCATTERING
SECONDARY EMISSION
SELENIDES
SELENIUM COMPOUNDS
SPECTROSCOPY
SYNCHROTRON RADIATION
THRESHOLD ENERGY
TRANSITION ELEMENTS
VALENCE