| 1. |
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| 2. |
- ANDERSEN, JN, et al.
(författare)
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SURFACE CORE-LEVEL SHIFTS OF INAS(110)
- 1990
-
Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 41:6, s. 3844-3846
-
Tidskriftsartikel (refereegranskat)
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| 3. |
- ANDERSEN, JN, et al.
(författare)
-
SURFACE RELATED CORE LEVEL SHIFTS FOR THE SI(111)SQUARE-ROOT-3X SQUARE-ROOT-3 - AL SYSTEM
- 1991
-
Ingår i: Journal of Vacuum Science & Technology B. - : American Vacuum Society. - 1071-1023 .- 1520-8567. ; 9:4, s. 2384-2387
-
Tidskriftsartikel (refereegranskat)abstract
- The Si(111) square-root 3 x square-root 3:Al reconstruction has been studied by surface sensitive high resolution core level spectroscopy. It is shown that three components are needed to fit the Si 2p spectra. The Al2p emission is found to consist of more than one component and it is argued that this is related to defects in the overlayer.
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| 4. |
- ANDERSSON, CBM, et al.
(författare)
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CORE-LEVEL PHOTOEMISSION FROM (III)-TYPE INAS SURFACES
- 1994
-
Ingår i: Journal de Physique IV. - : EDP Sciences. - 1155-4339 .- 1764-7177. ; 4:C9, s. 209-212
-
Tidskriftsartikel (refereegranskat)abstract
- The InAs(111)2x2 and InAs(($$$) over bar 111)1x1 surfaces have been studied with high resolution core level spectroscopy. For the InAs(($$$) over bar 111)1x1 surface both the In 4d and the As 3d core levels display strong surface core level shifts, while for the InAs(111)2x2 surface only the In 4d level shows a detectable surface shift. The results indicate that the InAs(($$$) over bar 111)1x1 surface is relaxed, with atom layer displacement extending to subsurface layers. Unexpectedly, we find no surface shifted anion core level for the InAs(111)2x2 surface.
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| 5. |
- ANDERSSON, CBM, et al.
(författare)
-
SPUTTERED AND ANNEALED INAS(111)OVER-BAR - AN UNRECONSTRUCTED SURFACE
- 1994
-
Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 307, s. 885-889
-
Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of the InAs(111BAR)1 X 1 surface has been investigated by angle resolved photoelectron spectroscopy along the symmetry lines GAMMAKBAR, GAMMAMBAR, and GAMMAMBAR of the surface Brillouin zone. The bulk valence band structure was calculated using a combination of the linear augmented plane-wave method and the relativistic augmented plane-wave method. We have projected the theoretical bulk band structure onto the surface Brillouin zone to separate surface states from surface resonances. Two surface related structures, S1 and S2, have been observed and their E(i)(k(parallel-to)) dispersions are established. Both S1 and S2 show the symmetry of the 1 X 1 surface Brillouin zone, which is consistent with the observed 1 X 1 LEED pattern. We identify S1 as the As-derived dangling bond state, and S2 is associated with the backbonds connecting the As atoms in the surface layer with the underlying In layer.
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| 6. |
- ANDERSSON, CBM, et al.
(författare)
-
SURFACE ELECTRONIC-STRUCTURE OF INAS(110)
- 1993
-
Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 47:4, s. 2427-2430
-
Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of the InAs(I 10) cleavage surface has been studied by angle-resolved photoelectron spectroscopy. The bulk band structure has been calculated utilizing the augmented plane-wave method and then the bulk bands have been projected along the lines GAMMA-XBARBAR and GAMMA-YBARBAR of the surface Brillouin zone (SBZ). Three surface-related structures have been found and their initial state versus k parallel-to dispersion along the line GAMMA-XBARBAR and the line GAMMA-YBARBAR of the SBZ has been determined. The structures are identified as A5, A4, and A3 along GAMMA-XBARBAR and as A5, A4, and C2 along GAMMA-YBARBAR.
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| 7. |
- Benson, Mikael, et al.
(författare)
-
Interleukin 6 response to urinary tract infection in childhood
- 1994
-
Ingår i: The Pediatric Infectious Disease Journal. - 0891-3668 .- 1532-0987. ; 13:7, s. 612-616
-
Tidskriftsartikel (refereegranskat)abstract
- This study analyzed the interleukin 6 (IL-6) response in 114 children with suspected urinary tract infection (UTI). Urine and serum samples were obtained at the time of enrollment. There were 90 children with UTI, 41 with and 49 without a temperature > or = 38.5 degrees C. The remaining 24 children did not have bacteriuria; 11 were febrile and 13 were not. The urinary IL-6 concentrations were higher in the children with UTI (mean, 129 units/ml) than in the children without bacteriuria (mean, 7 units/ml, P < 0.01). In contrast the serum IL-6 did not differ between children with or without UTI or between children with or without a temperature > or = 38.5 degrees C. The urinary IL-6 response was higher in children who were infected with P fimbriated Escherichia coli than in other children with UTI (P < 0.05). There was a correlation of urinary IL-6 with the degree of proteinuria, hematuria and urinary leukocyte counts (P < 0.001, P < 0.05, P < 0.05, respectively) but not with serum IL-6, CRP or temperature, and of serum IL-6 to C-reactive protein (P = 0.053) and renal concentrating capacity (P < 0.05). The results demonstrate that infections of the urinary tract activate an IL-6 response in children and that the magnitude of the IL-6 response is influenced by the properties of the infecting strain.
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| 8. |
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| 9. |
- CHAKARIAN, V, et al.
(författare)
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THE ADSORPTION OF I2 ON SI(111)-7X7 STUDIED BY SOFT-X-RAY PHOTOEMISSION
- 1993
-
Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 296:3, s. 383-392
-
Tidskriftsartikel (refereegranskat)abstract
- The adsorption Of I2 on Si(111)-7 x 7 at room temperature is studied with soft X-ray photoelectron spectroscopy. I2 adsorbs dissociatively, forming a mixture of SiI, SiI2 and SiI3 moieties, of which SiI dominates. The Fermi level is pinned near mid-gap, moving slightly towards the conduction band as the I coverage increases. The surface work function increases monotonically with I coverage. The I 4d core-level displays a single chemical state, which decreases in binding energy with increasing coverage. Analysis of the Si 2p core-level spectra shows that the adsorption proceeds first by attachment of I to the dangling bonds of the 7 x 7 unit cell and that, at saturation, 1.57 +/- 0.05 ML of I atoms are adsorbed in 1.10 +/- 0.02 ML of SiI(x) groups. These results indicate that substrate Si-Si bonds are broken by reaction with I2. The total I coverage is limited, however, by the availability Of surface dangling bonds that are required to initiate the dissociation Of I2 molecules.
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| 10. |
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| 11. |
- Engström, Tomas, 1950, et al.
(författare)
-
Some Findings from Learning of Assembly Work in Sweden
- 1992
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This publication is authored together with senior research competency within work organisation (professor Ulf Karlsson) (who rather inofficially functioned as a tutor for Engström during his PhD-studies, this was necessary since a full professor was lacking for several years at the Departement of Transportation) (in fact we both cooperated for a number of decades) (see some of the other publications registered Chalmer Public Library CPL).
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| 12. |
- GOTHELID, M, et al.
(författare)
-
FORMATION OF AN IODINE ZIGZAG CHAIN C(2X4) RECONSTRUCTION ON THE GE(111) SURFACE
- 1994
-
Ingår i: Microscopy Microanalysis Microstructures. - : EDP Sciences. - 1154-2799. ; 5:4-6, s. 277-282
-
Tidskriftsartikel (refereegranskat)abstract
- Room temperature adsorption of I-2 on the Ge(lll) surface is found to break the initial c(2 x 8) adatom reconstruction as iodine preferentially occupies the on top substrate site, breaks the backbonds between the adatom and the substrate and thus removes the Ge adatoms. As this process continues a c(2 x 4), and modifications thereof, reconstruction is formed consisting of chains of I-2 molecules bound in almost T-1 sites with a I-I bond length of 3.6 Angstrom.
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| 13. |
- GOTHELID, M, et al.
(författare)
-
GEOMETRY OF THE GE(111)-AU(ROOT-3X-ROOT-3)R 30-DEGREES RECONSTRUCTION
- 1994
-
Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 50:7, s. 4470-4475
-
Tidskriftsartikel (refereegranskat)abstract
- A structure model for the Ge(111)-Au(root 3X root 3)R30 degrees surface reconstruction is proposed based on scanning tunneling microscopy (STM) and photoelectron spectroscopy on the Ge 3d and Au 4f core lines. The basic unit is a Au3Ge molecule binding in one-third of the T-1 substrate sites with a gold trimer pointing out of the surface. This leaves two-thirds of a monolayer of unoccupied T-1 sites which make up a hexagonal honeycomb pattern. Two types of STM images have been obtained which are explained within this model, where either the trimers or the substrate Ge atoms are probed depending on the specific tip conditions in combination with the sample bias voltage. Furthermore, small insets of a metallic (1X1) structure are found at low gold coverage together with a distorted (2X2) surface structure.
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| 14. |
- GOTHELID, M, et al.
(författare)
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SN-INDUCED SURFACE RECONSTRUCTIONS ON THE GE(111) SURFACE STUDIED WITH SCANNING TUNNELING MICROSCOPY
- 1992
-
Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 271:3, s. L357-L361
-
Tidskriftsartikel (refereegranskat)abstract
- Scanning tunneling microscopy (STM) has been used to study different Sn induced reconstructions on the Ge(111) surface; namely the (7 x 7), (5 x 5) and (square-root 3 x square-root 3)R30-degrees structures. The first two have been confirmed to be of the dimer adatom stacking fault (DAS) type with adatoms mainly being Sn. The (square-root 3 x square-root 3)R30-degrees superstructure was found at different Sn depositions. At 0.4 monolayer (ML) Sn coverage a homogeneous Sn adatom layer is adsorbed on the (1 x 1) surface in threefold sites directly over second-layer atoms (T4), while at low coverage, 0.1 ML, the top layer is a mixture of Sn and Ge atoms. We also propose the chemical identities of the different atoms seen in the STM images as related to their apparent height.
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| 15. |
- GREHK, TM, et al.
(författare)
-
ADSORPTION OF POTASSIUM ON THE SI(111)ROOT-3X-ROOT-3R30-DEGREES - B-SURFACE - OBSERVATION OF AN INSULATING SURFACE AT SUBMONOLAYER COVERAGE
- 1993
-
Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 47:20, s. 13887-13890
-
Tidskriftsartikel (refereegranskat)abstract
- The Si(111) square-root 3 X square-root 3R 30-degrees:B surface with submonolayer coverages of potassium has been studied with angle-resolved photoelectron spectroscopy. Deposition of potassium leads to the formation of a state 0.7 eV below the Fermi level. The energy position of this state showed only a minor dependence on the actual potassium coverage and the state displayed a small dispersion of 0.1 eV when probed along the GAMMABAR-MBAR' direction in the square-root 3 X square-root 3R 30-degrees-surface Brillouin zone. These results support the idea that a mainly covalent bonding exists between the potassium atoms and the Si surface.
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| 16. |
- Haataja, Sauli, et al.
(författare)
-
Oligosaccharide-receptor interaction of the Galα1-4Gal binding adhesin of Streptococcus suis : Combining site architecture and characterization of two variant adhesin specificities
- 1994
-
Ingår i: Journal of Biological Chemistry. - 0021-9258. ; 269:44, s. 27466-27472
-
Tidskriftsartikel (refereegranskat)abstract
- The sugar binding specificities of two groups of Streptococcus suis, a pig pathogen that causes meningitis also in man, were determined. Both the group represented by a recently characterized strain inhibitable by galactose and N-acetylgalactosamine (type PN) and the group inhibitable by galactose (type PO) were found by hemagglutination and solid-phase binding inhibition experiments to recognize the disaccharide Galα1-4Gal of the P1 and Pk blood group antigens. Both types preferred the disaccharide in terminal position. PN showed some, whereas PO showed almost no, binding to the globoside oligosaccharide containing an additional GalNAcβ1-3 residue. The complete hydrogen bonding patterns were determined by using deoxy and other synthetic derivatives of the receptor disaccharide, and the constructed models of the interactions were compared with that of Escherichia coli PapG396 adhesin. The essential hydroxyls for binding were the HO-4', HO- 6', HO-2, and HO-3 hydroxyls on the β'α-side of the Galα1-4Gal molecule. Type PO adhesin also formed weak interactions with the hydroxyls HO-6 and HO-3'. The mechanism differed from that of E. coli, which binds to a cluster of five hydroxyls (HO-6, HO-2', HO-3', HO-4', and HO-6') and thus to a different part of the receptor disaccharide. These results represent the first example of the comparison of the saccharide receptor hydrogen bonding patterns of two bacterial organisms of different origin and show that the same saccharide may be recognized by two different binding mechanisms.
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| 17. |
- HAKANSSON, MC, et al.
(författare)
-
DIMER FORMATION AND ELECTRONIC-STRUCTURE ON THE GE(100)(2X1)-SB SURFACE
- 1992
-
Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 278:1-2, s. L131-L134
-
Tidskriftsartikel (refereegranskat)abstract
- Deposition of antimony on Ge(100)2 X 1 results in a well-ordered, highly passivated surface. From a comparison between core-level data and angle-resolved photoemission data, we conclude that the observed 2 x 1 reconstruction is caused by the formation of symmetric Sb-Sb dimers on the Ge surface.
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| 18. |
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| 19. |
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| 20. |
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| 21. |
- HIMPSEL, FJ, et al.
(författare)
-
FINE-STRUCTURE OF THE CA 2P X-RAY-ABSORPTION EDGE FOR BULK COMPOUNDS, SURFACES, AND INTERFACES
- 1991
-
Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 43:9, s. 6899-6907
-
Tidskriftsartikel (refereegranskat)abstract
- The fine structure of the Ca 2p soft-x-ray-absorption edge is studied for a variety of bulk compounds (Ca metal, CaSi2, CaO, and CaF2), for surfaces and interfaces [CaF2(111), BaF2 on CaF2(111), Ca and CaF2 on Si(111)], and for defects (F centers in CaF2). The observed multiplet structure is explained by atomic calculations in a crystal field [cubic O(h) for the bulk and threefold C3-nu for the (111) surfaces and interfaces]. While the bulk spectra are isotropic, the surface and interface spectra exhibit a pronounced polarization dependence, which is borne out by the calculations. This effect can be used to become surface and/or interface selective via polarization-modulation experiments, even for buried interfaces. A change in valence from Ca2+ to Ca1+ causes a downwards energy shift and extra multiplet lines according to the calculation. The energy shift is observed for F centers at the CaF2 surface and for the CaF2/Si(111) interface.
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| 22. |
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| 23. |
- JOHANSSON, LI, et al.
(författare)
-
CORE LEVEL PHOTOEMISSION-STUDY OF CR3SI(100)
- 1991
-
Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 251, s. 101-107
-
Tidskriftsartikel (refereegranskat)abstract
- High resolution photoemission studies of the core levels in Cr3Si have been carried out using synchrotron radiation. Investigations were performed both on the clean surface, cleaned in situ by sputter and annealing cycles, and after oxygen exposures. A surface shifted Si 2p component was observed on the annealed surface but no surface shifted component could be identified in the Cr 3p spectrum. The surface shift was extracted using a curve fitting procedure and found to be -0.30(5) eV. The shift expected due to the loss of coordination at the surface is found to be negative but of about half the size of the observed shift. Upon oxygen adsorption at room temperature a chemically shifted Si 2p component appeared already after an exposure of < 1 L, indicating rapid silicon oxidation, while a chemically shifted Cr 3p component could be resolved only after exposures of about 10 L. These findings are presented and discussed.
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| 24. |
- JOHANSSON, LI, et al.
(författare)
-
SURFACE-SHIFTED CORE LEVELS IN MO3SI (100) AND (110)
- 1991
-
Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 43:15, s. 12355-12363
-
Tidskriftsartikel (refereegranskat)abstract
- High-resolution photoemission studies of core levels in Mo3Si have been carried out using synchrotron radiation. Surface-shifted Si 2p components were observed on annealed (100) and (110) crystal faces and were unambiguously identified in adsorption experiments of hydrogen and oxygen. The surface core-level shifts were extracted using a curve-fitting procedure. For the (110) surface one shifted component was identified having a surface shift of -1.02(1) eV. For the (100) surface two shifted components were found to be necessary in order to model the experimental spectrum, the stronger component having a shift of -0.68(2) eV and the weaker a shift of -1.03(4) eV. No surface-shifted components could be identified in the Mo 4p photoelectron spectrum. Upon oxygen adsorption a chemically shifted Si 2p component was observed, indicating silicon oxidation, while no chemically shifted component appeared in the Mo 4p spectrum. In the Si 2p spectrum pronounced photoelectron-diffraction effects were observed both as a function of photoelectron kinetic energy and emission angle. These findings are presented and discussed.
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| 25. |
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| 26. |
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| 27. |
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| 28. |
- Leckner, Bo G, 1936, et al.
(författare)
-
Emissions from a 165 MWth FBC steam boiler
- 1992
-
Ingår i: Wirbelschichtsysteme 1992, VGB-TB214. ; :V28, s. 1-13
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Measurements of NO, N2O, SO2 and limestone utilization were measures on a 165 MW boiler as a function of bed temperature, excess air, and molar Ca/S ratio.
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| 29. |
- LELAY, G, et al.
(författare)
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CORE-LEVEL SPECTROSCOPY STUDY OF THE INITIAL FORMATION OF TIN GERMANIUM INTERFACES
- 1992
-
Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 56-8, s. 178-184
-
Tidskriftsartikel (refereegranskat)abstract
- We have studied the initial stages of the Schottky barrier formation at Sn/Ge(100) interfaces, in comparison with Sn/Ge(111) ones, with high resolution core-level spectroscopy measurements (Ge 3d and Sn 4d shallow core levels) using synchrotron radiation. A detailed, stringent decomposition of the core lines reveals three different components for both Ge and Sn on the two surfaces. The three components of the Sn 4d line on the Ge(100)2 x 1-Sn surface are interpreted as due to three different adsorption sites simultaneously occupied, while the persistence of the surface components in the Ge 3d core lines suggests that the building block of the reconstruction remains an asymmetric Ge dimer.
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| 30. |
- LELAY, G, et al.
(författare)
-
ELECTRONIC-PROPERTIES OF CLEAVED(110) AND MBE-GROWN(100) INAS SURFACES, CLEAN AND COVERED WITH AN ULTRA-THIN AG ADLAYER
- 1993
-
Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 70-1, s. 502-506
-
Tidskriftsartikel (refereegranskat)abstract
- The initial electronic structure of the pseudomorphic InAs/GaAs(100) heterostructure as well as that of the Ag/InAs(110) interface at 20 K have been studied by synchrotron radiation photoelectron spectroscopy. In the first case we find that the valence band spectra show no evidence for the formation of bulk-like energy bands. In the second case we prove for the first time that upon deposition of minute amounts of Ag at low temperature onto cleaved InAs(110) substrates one induces a giant movement of the Fermi level well into the conduction band thus creating a strong two-dimensional electron channel at the surface.
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| 31. |
- LELAY, G, et al.
(författare)
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STM AND SYNCHROTRON-RADIATION STUDIES OF PROTOTYPICAL METAL-SEMICONDUCTOR SYSTEMS
- 1994
-
Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 307, s. 280-294
-
Tidskriftsartikel (refereegranskat)abstract
- Since the origin of surface science noble metal/elemental semiconductor couples have been considered as ''prototypical'' systems. After three decades of research their structural and electronic properties remain an intriguing maze despite recent advances made, especially thanks to the development of the near-field microscopies and the ''tensive use of synchrotron radiation in surface crystallography and in high-resolution photoelectron spectroscopy. In the last few years, lead, as a replacement inert metal, has nearly gained the pole position in the display of exotic behaviour. This paper gives a flavour of this mystery story and highlights some puzzling questions.
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| 32. |
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| 33. |
- LELAY, G, et al.
(författare)
-
SURFACE CORE-LEVEL SHIFTS ON GE(100) - C(4X2) TO 2X1 AND 1X1 PHASE-TRANSITIONS
- 1992
-
Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 45:12, s. 6692-6699
-
Tidskriftsartikel (refereegranskat)abstract
- By comparing, under identical experimental conditions, high-resolution synchrotron-radiation core-level photoemission spectra taken from both Ge(111) and Ge(100) samples, we establish that the decomposition of the Ge 3d lines from the clean Ge(100) 2 x 1 surface at room temperature requires two surface components shifted by -0.23 and -0.60 eV relative to the bulk one. This deconvolution is fully consistent with the asymmetric-dimer reconstruction model of this surface. We further study the reversible phase transitions that occur on this surface: 2 x 1 <--> c(4 x 2) at low temperature; 2 x 1 <--> 1 x 1 at high temperature. We show from both core-level and valence-band studies that the number of dimer bonds is essentially conserved in these transitions. We also suggest, by comparing a dimer with an Ising spin, that these transitions correspond, respectively, to an antiferromagnetic ordering at low temperatures and to a paramagnetic disordering at high temperatures.
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| 34. |
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| 35. |
- Nyholm, R., et al.
(författare)
-
ADSORPTION-SITE DETERMINATION OF ORDERED YB ON SI(111) SURFACES
- 1993
-
Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 47:15, s. 9663-9668
-
Tidskriftsartikel (refereegranskat)abstract
- Low-energy-electron-diffraction (LEED), scanning-tunneling-microscopy (STM), and photoelectron-spectroscopy measurements have been performed on the ordered submonolayer surface reconstructions of Yb on Si(111). Two of these reconstructions, namely, 3 X 1 and 2 X 1, have been studied in detail. STM and LEED revealed that what was considered to be the 3 X 1 reconstruction is actually a 3 X 2 reconstruction. By combining STM and photoelectron-spectroscopy results from the 3 X 2 and 2 X 1 reconstructions, we conclude that the Yb atoms are adsorbed in bridge sites.
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| 36. |
- Nyholm, R., et al.
(författare)
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ELECTRONIC AND STRUCTURAL-PROPERTIES OF THE CU-BI2CASR2CU2O8 INTERFACE
- 1991
-
Ingår i: Physica. C, Superconductivity. - 0921-4534 .- 1873-2143. ; 180:1-4, s. 120-123
-
Tidskriftsartikel (refereegranskat)abstract
- The formation of the Cu-Bi2CaSr2Cu2O8 interface has been studied by photoelectron spectroscopy using synchrotron radiation. Photon energies in the range 20-1000 eV were utilized in order to probe both the valence band and to monitor chemical changes upon Cu deposition, as revealed by the core-level shifts. A strong chemical reaction between Bi2CaSr2CuO8 and Cu is manifested by the formation of metallic Bi. From the intensity variations as a function of electron emission angle it is shown that the metallic Bi segregates to the top surface layer.
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| 37. |
- Nyholm, R., et al.
(författare)
-
EPITAXIAL SILICIDE FORMATION IN THE MG/SI(111) SYSTEM
- 1993
-
Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 289:3, s. 290-296
-
Tidskriftsartikel (refereegranskat)abstract
- The silicide formation has been studied in the Mg/Si(111) system by IOW energy electron diffraction (LEED) and photoelectron spectroscopy. It has been found that an epitaxial Mg2Si silicide is responsible for the (2/3 square-root e x 2/3 square-root 3)R30-degrees reconstruction in this system. The thickness of the silicide is limited due to the very low formation temperature for this silicide. The Fermi level is positioned 0.59 +/- 0.06 eV above the valence band maximum in the Si substrate and the valence band maximum in the epitaxial silicide is positioned 0.3 +/- 0.1 eV below the Fermi level.
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| 38. |
- Nyholm, R., et al.
(författare)
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FORMATION OF SM SILICIDES ON SI(111) - COMPOSITION AND EPITAXY
- 1993
-
Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 293:3, s. 254-259
-
Tidskriftsartikel (refereegranskat)abstract
- The formation of Sm silicides on Si(111) by means of solid phase epitaxy has been studied with low energy electron diffraction, Auger electron spectroscopy and photoelectron spectroscopy of the Sm 4f level and Si 2p level. A limited reaction is found to occur already at room temperature whereas at higher temperatures a strongly intermixed Sm/Si layer showing some long range order is formed. The Sm atoms of this intermixed phase are found to be completely trivalent in accordance with expectations. The intermixed layer consists of two silicides with different compositions, one of them being SmSi2-x, the other being tentatively ascribed to SmSi.
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| 39. |
- Nyholm, R., et al.
(författare)
-
PHOTOEMISSION-STUDY OF THE BI2CASR2CU2O8 SUPERCONDUCTOR WITH CU, AG AND AU OVERLAYERS
- 1993
-
Ingår i: Physica. C, Superconductivity. - 0921-4534 .- 1873-2143. ; 218:1-2, s. 103-108
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present a photoemission study of the interaction of Cu, Ag and Au with clean single-crystal Bi2CaSr2Cu2O8 superconductor surfaces. Both the valence-band and the Bi 5d, O 1 s and Sr 3d core levels were monitored for all overlayers. Cu, Ag and Au were deposited as consecutively thicker layers starting with a third of a monolayer and progressing in steps up to a deposition in the range of eight monolayers. Comparing the results for the different overlayers reveals the Ag overlayer to be less reactive than Au which causes the formation of metallic Bi on cleaved Bi2CaSr2Cu2O8 surface. Cu is shown to be the most reactive of the three metals. The Au and Ag overlayers display an island-growth mode, while Cu grows in a layer-by-layer fashion.
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| 40. |
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| 41. |
- QU, H, et al.
(författare)
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ANGLE-RESOLVED PHOTOELECTRON-SPECTROSCOPY STUDY OF THE SURFACE ELECTRONIC-STRUCTURE OF ZNTE(110)
- 1991
-
Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 43:12, s. 9843-9850
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Tidskriftsartikel (refereegranskat)abstract
- The valence-electronic structure of the ZnTe(110) surface has been studied by angle-resolved photoelectron spectroscopy using synchrotron radiation. The bulk valence bands and, in particular, the energies at the GAMMA and X points have been extracted from normal-emission data. Several surface-related structures have been identified in off-normal-emission data, from which band structures of surface states and resonances have been derived.
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| 42. |
- QU, H, et al.
(författare)
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ANGLE-RESOLVED PHOTOEMISSION-STUDIES OF THE CDTE(110) SURFACE
- 1991
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 43:18, s. 14589-14596
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of the CdTe(110) surface has been studied with angle-resolved photoelectron spectroscopy using synchrotron radiation. An empirical tight-binding linar combination of atomic orbitals band structure has been derived, based on normal-emission spectra. Several, previously unreported, surface-related states have been observed in off-normal emission, and their dispersions have been mapped along symmetry directions of the surface Brillouin zone.
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| 43. |
- QU, H, et al.
(författare)
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BULK AND SURFACE ELECTRONIC-STRUCTURE OF ZNSE(110)
- 1991
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 44:4, s. 1762-1766
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Tidskriftsartikel (refereegranskat)abstract
- The valence-electronic structure of the ZnSe(110) surface has been studied by angle-resolved photoelectron spectroscopy using synchrotron radiation. The bulk energy bands along the GAMMA-KX direction have been mapped with use of normal-emission spectra in the 16-70-eV photon-energy range. Off-normal-emission spectra were measured along the GAMMA-BAR XBAR, GAMMA-BAR YBAR, and GAMMA-BAR MBAR symmetry lines. Several surface-related structures have been deduced from these data and their dispersions have been determined.
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| 44. |
- QU, H, et al.
(författare)
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SURFACE ELECTRON-STRUCTURE OF INP(110) STUDIED WITH ANGLE-RESOLVED PHOTOELECTRON-SPECTROSCOPY
- 1991
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Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 255:3, s. 237-244
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Tidskriftsartikel (refereegranskat)abstract
- The surface electron structure of InP(110) has been studied by means of synchrotron radiation excited angle-resolved photoelectron spectroscopy. After identifying the bulk-related spectral structures, the surface-induced energy bands have been mapped along symmetry directions. The polarization dependence of the surface-related structures is discussed.
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| 45. |
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| 46. |
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| 47. |
- QVARFORD, M, et al.
(författare)
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X-RAY-ABSORPTION AND RESONANT-PHOTOEMISSION STUDY OF CA IN THE HIGH-TEMPERATURE SUPERCONDUCTOR BI2SR2CACU2O8
- 1992
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 46:21, s. 14126-14133
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of Ca in the high-temperature superconductor Bi2Sr2CaCu2O8 has been studied by x-ray-absorption spectroscopy and resonant-photoemission at the Ca L2,3 absorption edge. In the x-ray-absorption spectrum no edge structure is seen at the energy corresponding to the Ca 2p3/2 core-level binding energy, in agreement with the very low Ca density of states at the Fermi level predicted by band-structure calculations. Furthermore, the crystal-field splitting of the Ca 3d level, which is characteristic of ionic Ca compounds, is clearly observed in the x-ray-absorption spectrum. The photoemission spectra display strong resonant enhancements of the Ca 3s and 3p core levels as well as strong changes in the intensity and the line shape of the Ca L2,3M2,3M2,3 Auger structure at the Ca L2,3 threshold, showing the localized nature of the 3d states in core ionized Ca. The 3d induced spectator shift of the Ca L2,3M2,3M2,3 complex is fairly small as compared to what has been reported for CaF2, indicating that the screening of the normal Auger final state by the charge carriers in the surrounding Cu-O2 layers is quite efficient. From the Ca L2,3M2,3M2,3 data it is also suggested that, at the Ca L2 threshold, the excited 3d electron participates in a Coster-Kronig-type decay resulting in a 2p3/2 core hole followed by a normal L3M2,3M2,3 Auger decay.
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| 48. |
- ROGELET, T, et al.
(författare)
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ELECTRONIC-STRUCTURE OF NIO(1 0 0) WITH ADSORBED NA
- 1993
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Ingår i: Solid State Communications. - 0038-1098 .- 1879-2766. ; 85:7, s. 657-660
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Tidskriftsartikel (refereegranskat)abstract
- Adsorption of Na on single crystals of NiO(1 0 0) at room temperature has been investigated via angle-resolved photoemission spectroscopy and measurements of work-function changes. The drastic changes in the valence band spectra upon Na deposition are assigned to a chemical reaction between Na and O where metallic Ni is left as by-product. At short deposition times, Na mainly acts as an inert electron donor, and at these coverages no dispersion is observed in the angle-resolved photoemission spectra which indicates that the electronic states are localized. The measurements were performed both for a polished and an in-situ cleaved NiO crystal.
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| 49. |
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| 50. |
- TORNEVIK, C, et al.
(författare)
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ADSORPTION OF SN ON SI(111)7X7 - RECONSTRUCTIONS IN THE MONOLAYER REGIME
- 1994
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Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 314:2, s. 179-187
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Tidskriftsartikel (refereegranskat)abstract
- Different monolayer phases of Sn on Si(111)7 x 7 have been studied by means of scanning tunneling microscopy (STM), core-level photoelectron spectroscopy (XPS), and Rutherford backscattering spectrometry (RBS). The STM results show that square-root 3 x square-root 3 reconstructions are obtained for room-temperature deposition of 1/3 ML of Sn followed by sample annealing in a broad temperature range. A T4 Sn adatom square-root 3 x square-root 3 phase is formed for temperatures between 500 and 800-degrees-C, with a concentration of defects that is strongly dependent on the temperature and which is as high as 25% for the lowest temperatures. Above 825-degrees-C a second square-root 3 x square-root 3 adatom reconstruction is formed, a mosaic-like phase with a 1: 1 mixture of Si and Sn atoms in T4 positions. The results from investigations of the higher coverage 2 square-root 3 x 2 square-root 3 reconstruction by XPS and RBS support the theory that this phase is a two-layer epitaxial Sn structure with all Si(111) dangling bonds saturated. The Sn coverage for this phase was determined to be between 1 and 1.2 ML.
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