Filtyp
The performance of a scanning photoelectron microscope at the MAX I storage ring in Lund is presented. The microscope utilizes undulator radiation in the energy range 15-150 eV and is comprised of a plane-grating monochromator with a Kirkpatrick-Baez objective and a gracing incidence ellipsoidal focusing mirror. The instrument with its high photon flux, 109-1010 photons/s, and narrow bandwidth, be
High resolution core level photoemission measurements are reported of the binding energy shifts of the 3d core level of Mo, Rh and Pd atoms in interfaces between these 4d metals and alkali metals. The core level binding energies of the interface 4d atoms are found to be almost equal to those of the clean surface atoms for Mo and Rh. For Pd a large alkali induced shift towards higher binding energy
Core level binding energy shifts from approximately three layers of different alkali metals deposited on Pd(111), Pd(100), Rh (111), and Rh (110) are presented in order to demonstrate how the packing of the substrate surface affects the layer-resolved alkali core level binding energy shifts. It is found that a more open surface induces a larger alkali core level binding energy shift. It is shown t
Utilizing monochromatized synchrotron radiation strong photoemission enhancements in the valence-band region and the Cu 3p core level have been measured in the vicinity of the Cu L3 threshold of Bi2Sr2CuO6 and Bi2Sr2CaCu2O8 superconductors. For both the valence-band and the Cu 3p level in both crystals the satellite structures show the strongest enhancements. The line shapes of these enhanced sate
The dynamics of the temperature induced transformation between low and high temperature adsorption phases of Rb on Al(111) has been followed by high resolution core level spectroscopy. Particular emphasis has been paid to the order-preserving transformation between the low and high temperature Al(111)-Rb-(√3 × √3)R30° structures in which Rb atoms occupy on-top and substitutional sites, respectivel
A photoemission study of the Be(112̄0) surface carried out at a sample temperature of 100 K is reported. A surface shifted Be 1s component, having a shift of - 410 meV, is resolved on this surface. The extracted surface to bulk intensity ratio indicate that this component originates from atoms in the surface layer only. This is opposite to previous observations on both the close-packed
Core-level binding energy shifts of Cs induced by changes in the surroundings of the Cs atoms are measured for two different Cs core levels, 5p and 4d, and are found to be different for these two levels. The surface core-level shift of Cs is found to differ by 25 meV between the two levels. In the case of the Cs core-level shifts between bulk Cs atoms and Cs atoms at an interface between Cs and an
Photoemission from different alkali core levels (Na 2p, K 3p, Rb 4p, and Cs 4d) has been studied for thin alkali films deposited on four different 4d metal surfaces: Mo(110), Rh(111), Rh(110), and Pd(100). Alkali atoms at the interface, the bulk, and at the surface of the adsorbed alkali film are found to have different core-level binding energies. It is found that the core-level binding-energy sh
The low temperature coadsorption of Na and Rb on an Al(111) surface is examined with a combination of LEED and core level photoemission spectroscopy. We observe LEED pattern sequences and alkali core level binding energies which are consistent with a net total alkali coverage and can be explained by Na-Rb repulsion, segregation, and islanding, though other models cannot be definitely excluded.
The synchrotron-radiation-induced Auger and photoelectron spectra of the xenonlike ions I- (in CsI), Cs+ (in CsI), Ba2+ (in BaF2), and La3+ (in LaF3) have been measured in the vicinity of the M4,5 absorption edges of these ions. It is shown that the spectra of La and Ba measured at 3d10→3d94f resonances exhibit a very intense 4f-spectator structure which changes its energy and intensity with the e
High resolution measurements are reported of the surface core-level shift of the 3d level for the Rh(111), Rh(110), Pd(111), Pd(110), and Ag(111) single-crystal surfaces. These measurements and earlier ones for the Mo(110), Rh(100), and Pd(100) surfaces are analyzed by ab initio calculations of the surface core-level shift. The calculations are found to reproduce well the trends of the experimenta
A high-resolution photoemission study of the Be (101̄0) surface, at a sample temperature of 100 K, is reported. Three surface-shifted Be 1s components are revealed having shifts of -700, -500, and -220 meV. These are interpreted as originating from the first, second, and third plus fourth atomic layers while the bulk signal originates from the fifth and deeper layers. The surface layer shift for t
The inner valence region of CO/Pd(100) p(2 square root 2* square root 2)R45 degrees has been studied by angular resolved photoemission at the Pd 4d Cooper minimum, and with resonant Auger spectroscopy at photon energies corresponding to the C 1s and O 1s X-ray absorption (XA) maxima of the unoccupied parts of the 2 pi *-Pd 4d hybrid (2 pi un). Previously unobserved inner valence states are reveale
In situ condensation of an amorphous cap of the high vapour pressure element (i.e. As, Sb) has been found to provide effective protection of molecular beam epitaxy grown compound semiconductor surfaces against ambient contamination. Most work reported so far relates to arsenic-capped AlGaAs. Detailed investigation with surface sensitive structural (RHEED, LEED) and chemical (XPS) probes confirms t
The surface core-level shift of the Mo(110) surface is determined from high-resolution photoemission measurements of the Mo 3d level. The 3d core-level binding energy of the surface atoms is found to be lowered by 333±10 meV relative to that of the bulk atoms. This result agrees well with semiempirical estimates and with the results of recent ab initio calculations. Decompositions of the spectra i
High-resolution photoemission studies of oxidation of the Al(111) surface have been performed. The appearance of a component at lower binding energy than the metallic bulk Al emission in the Al 2p spectrum at oxygen exposures above ∼50 langmuir (1 L = 10-6 Torr s) is argued to be due to Al atoms which do not bond directly to oxygen atoms at the oxide-metal interface. Low-energy electron diffractio
Layer resolved core level spectra are presented for Na, K, Rb and Cs films on Al(111). From the development of the spectra, it is possible to distinguish emission from alkali atoms at the interface, in the bulk, and at the surface of the adsorbed layers. The core level binding energy shifts are discussed in terms of adhesion and interface segregation energies. It is found experimentally that the A
Low-energy electron diffraction, scanning tunneling microscopy, and photoelectron spectroscopy results from the submonolayer Sm- and Yb-induced surface structures are presented. Several similar metal-induced surface reconstructions are found to exist for Yb and Sm on Si(111) for low submonolayer coverages: 3×2, 5×1, and 7×1. At higher submonolayer coverage, Yb induces a 2×1 reconstruction while Sm
The results of a high resolution photoemission study of the Be(0001) surface carried out at temperatures between 100 and 450 K are reported. At 100 K, three distinctly shifted Be 1s levels, exhibiting shifts of -825, -570, and -265 meV, are revealed and interpreted to originate from the three outermost atomic layers. Identification of two subsurface core level shifts and a first layer surface shif
Taking advantage of the linear polarisation of synchrotron radiation, the polarisation dependence of the O K and Cu L3 X-ray absorption edges has been compared for in situ cleaved Bi2Sr2CaCu2O8 and Bi2Sr2CuO6 single crystals. The X-ray absorption spectra were measured by means of total electron yield detection. The spectra show for both crystals that the lowest unoccupied Cu 3d and O 2p orbitals a
