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- Göthelid, M., et al.
(författare)
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Adatom and rest-atom contributions in Ge(111)c(2×8) and Ge(111)-Sn(7×7) core-level spectra
- 1993
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Ingår i: Physical Review B. - 0163-1829. ; 48:3, s. 2012-2015
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Tidskriftsartikel (refereegranskat)abstract
- We have identified the adatom contribution in the Ge 3d core-level spectra from the clean Ge(111)c(2×8) surface, shifted 0.17 eV to higher binding energy compared to the bulk. This adatom component vanishes in the Ge(111)-Sn(7×7) surface core-level spectra where Sn occupies the adatom site. Moreover we report the observation of an earlier proposed difference between the rest atoms in the c(2×8) structure, and also a shift to lower binding energy for the rest atoms in both structures studied. © 1993 The American Physical Society.
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- Le Lay, G., et al.
(författare)
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STM and synchrotron radiation studies of "prototypical" metal{plus 45 degree rule}semiconductor systems
- 1994
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Ingår i: Surface Science. - 0039-6028. ; 307-309:PART A, s. 280-294
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Tidskriftsartikel (refereegranskat)abstract
- Since the origin of surface science noble metal{plus 45 degree rule}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 extensive 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. © 1994.
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- Törnevik, C., et al.
(författare)
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Adsorption of Sn onSi(111)7 × 7 : reconstructions in the monolayer regime
- 1994
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Ingår i: Surface Science. - 0039-6028. ; 314:2, s. 179-187
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Tidskriftsartikel (refereegranskat)abstract
- Different monolayer phases of Sn on Si(111)7 × 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 3 × 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 3 ×3 phase is formed for temperatures between 500 and 800°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°C a second 3×3 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 3 × 2 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. © 1994.
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- Alfredsson, Viveka, et al.
(författare)
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In-situ studies of the formation mechanism of SBA-15
- 2005
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Ingår i: Nanoporous Materials IV, 156. - 0444517480 ; 156, s. 69-74
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Konferensbidrag (refereegranskat)abstract
- The formation process of SBA-15 has been investigated by time resolved TEM, in-situ SAXS/SAXD and in-situ NMR. The synthesis was done at 35 degrees in acidic solution with tetramethylorthosilicate as the silica source and Pluronic P123 as the structure directing amphiphile. The initially formed silica-polymer composite consists of flocs of spherical micelles in a silica matrix. The micelles then coalesce forming rods that eventually pack into the ordered array of which SBA-15 consists.
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- Göthelid, M., et al.
(författare)
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Sn-induced surface reconstructions on the Ge(111) surface studied with scanning tunneling microscopy
- 1992
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Ingår i: Surface Science. - 0039-6028. ; 271:3, s. L357-L361
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Tidskriftsartikel (refereegranskat)abstract
- Scanning tunneling microscopy (STM) has been used to study different Sn induced reconstructions on the Ge(111) surface; namely the (7 × 7), (5 × 5) and ( 3 × 3) R30° structures. The first two have been confirmed to be of the dimer adatom stacking faults (DAS) type with adatoms mainly being Sn. The ( 3 × 3)R30° superstructure was found at different Sn depositions. At 0.4 monolayer (ML) Sn coverage a homogeneous Sn adatom layer is adsorbed on the(1 × 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. © 1992.
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