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X-ray absorption study of oxygen in the high-Tc superconductor Bi2Sr2CaCu2O8 near the interfaces to Cu, Ag and Au

The influence on O 2p holes in single crystalline Bi2Sr2CaCu2O8 upon the interface formation to Cu, Ag and Au has been studied by O K edge X-ray absorption measurements. It was found that Cu reduces the amount of doping induced O 2p holes significantly in the vicinity of the interface, whereas Ag and Au gave a much smaller reduction of these states. Photoemission spectra confirmed previous finding

Photoemission and x-ray absorption study of superconducting and semiconducting Ba1-xKxBiO3 single crystals

Semiconducting Ba0.9K0.1BiO3 and superconducting Ba0.6K0.4BiO3 single crystals cleaved in situ have been studied by core level and valence band photoelectron spectroscopy and O K edge x-ray absorption spectroscopy. It was found that the general shape of the valence band spectrum agrees with the shape predicted by band structure calculations, but the intensity near the Fermi level was lower in the

Doping dependence of the O 1s core-level photoemission in Bi-Sr-Ca-Cu-O superconductors

The O 1s core level of three different Bi-Sr-Ca-Cu-O superconductors has been studied by means of high-resolution x-ray-photoelectron spectroscopy (XPS) and x-ray-absorption spectroscopy (XAS). The O 1s XPS spectra could be decomposed into three components that were unambiguously assigned to the emission from the three different oxide layers in the crystal structure. These are, in order of increas

Core-level satellite excitations of K/Al(100) and K/Al(111)

Alkali-metal-induced satellite peaks associated with the K 3p and Al 2p core levels have been measured with photoemission for K/Al(111) and K/Al(100) under both low- and room-temperature preparation conditions. For low-temperature deposition we observedddd loss peaks in good agreement with electron-energy-loss spectroscopy studies of analogous systems which we assign to the excitation of collectiv

Design of a compact varied-line space grating monochromator for enhanced flux at MAXLAB

For soft x-ray fluorescence spectroscopy with selective energy excitation, it is desirable to have maximum flux at moderate resolution. A plane grating monochromator with varied line spacing can be used in the convergent beam of an ellipsoidal focusing mirror to provide moderate resolution with a large collection angle and minimum number of reflecting surfaces. We determine the design parameters f

Thermal effects of undulator radiation on Si optics for a plane grating monochromator

Insertion devices on the third-generation 1.5 GeV electron storage ring MAX II will subject the grazing incidence mirrors and gratings of new soft x-ray beamlines to high thermal loads. These thermal loads will cause distortion in the optical surfaces which can be reduced to acceptable levels by the proper choice of substrate material and cooling. A finite element analysis of the temperature varia

The vacuum ultraviolet scanning photoelectron microscope at MAX-LAB

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

Core level binding energy shifts in interfaces between 4d and alkali metals

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

Alkali core level binding energy shifts from buried interfaces between alkali films and metallic substrates with different surface index

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

Resonant valence-band and Cu 3p photoemission at the Cu L3 threshold of Bi2Sr2CuO6 and Bi2Sr2CaCu2O8

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

On the temperature induced transformation between the two Al(111)-(√3 × √3)R30°-Rb structures

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

Surface core level shift on Be( 112̄0)

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

Differences in the Cs 4d and 5p surface and interface core-level shifts

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

Alkali core-level binding-energy shifts in alkali/4d-metal interface systems

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

Alkali-alkali interactions on Al(111) : segregation and islanding in Na-Rb mixtures

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.

M4,5N4,5N4,5 Auger decay spectra of the resonantly excited 3d94f configuration of xenonlike ions in solids

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

Surface core-level shifts of some 4d-metal single-crystal surfaces : Experiments and ab initio calculations

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

Core-level shifts on Be(101̄0)

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 adsorbed on Pd(100)

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

As capping of MBE-grown compound semiconductors; novel opportunities to interface science and device fabrication

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