PROPERTIES OF ULTRATHIN Sb LAYERS ON THE Ni(111) FACE

2003 ◽  
Vol 10 (01) ◽  
pp. 65-72 ◽  
Author(s):  
A. KRUPSKI ◽  
S. MRÓZ
Keyword(s):  
Atomic Structure ◽  
Electron Spectroscopy ◽  
Atomic Layer ◽  
Text Structure ◽  
Elastic Peak ◽  
Low Energy Electron Diffraction ◽  
Structure And Morphology ◽  
Text Structures ◽  
First Results ◽  
Low Energy Electron

We present the first results concerning the atomic structure and morphology of ultrathin Sb layers deposited on the Ni(111) face in ultrahigh vacuum at the substrate temperature ranging from 150 to 700 K obtained with the use of Auger electron spectroscopy (AES), low-energy electron diffraction (LEED) and directional elastic peak electron spectroscopy (DEPES). The AES results indicate that the antimony layer on the Ni(111) at T < 200 K grows in the Frank–van der Merwe mode. For temperature around 250 K, the flat two atomic layer islands ("wedding cakes") seem to grow after completion of the first antimony monolayer. At T ≥ 300 K , a Sb–Ni surface alloy is formed. DEPES measurements indicate that the atomic structure of Sb layers deposited at T = 150 K is completely amorphous, while better and better pronounced maxima appear in DEPES profiles when the sample temperature increases from 300 to 450 K. LEED patterns corresponding to p(1 × 1), p(2 × 2) and [Formula: see text] structures have been observed for 150 K ≤ T ≤ 250 K . A possible model for the last structure is proposed. After annealing the deposited layer at T > 500 K , the [Formula: see text] structure appears.

CHEMICAL RECONSTRUCTION OF THE TiAl(010) SURFACE

1995 ◽  
Vol 02 (02) ◽  
pp. 183-189 ◽  
Author(s):  
C.P. WANG ◽  
S.K. KIM ◽  
F. JONA ◽  
D.R. STRONGIN ◽  
B.-R. SHEU ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Atomic Structure ◽  
Atomic Layer ◽  
Interlayer Spacing ◽  
Low Energy ◽  
Intensity Analysis ◽  
Low Energy Electron Diffraction ◽  
Surface Phases ◽  
Low Energy Electron ◽  
Bulk Structure

The atomic structure of a clean (010) surface of the ordered binary alloy TiAl (with tetragonal bulk structure of the CuAu I type) is studied with quantitative low-energy electron diffraction (QLEED). Two different surface phases are found depending on the preparation procedure. After a cleaning step in vacuo by means of Ar-ion bombardments, anneals at 750−850°C produce a 2×1 surface and anneals at about 900° C produce a 1×1 surface. A QLEED intensity analysis of the 1×1 structure reveals the occurrence of chemical reconstruction, whereby the Ti atoms in the first layer exchange places with the Al atoms in the second layer. Thus, while any bulk (010) plane contains 50% Al and 50% Ti , the top atomic layer of a (010) surface contains 100% Al and the second atomic layer contains 100% Ti . Both layers are slightly buckled and the first interlayer distance is compressed about 7.1% while the second interlayer spacing is expanded about 7.4% with respect to the bulk value.

ADSORPTION SITE CHANGE FOR Cs, Rb OR K ADSORPTION ON Ag(111)

1997 ◽  
Vol 04 (06) ◽  
pp. 1215-1219 ◽  
Author(s):  
P. KAUKASOINA ◽  
M. LINDROOS ◽  
G. S. LEATHERMAN ◽  
R. D. DIEHL
Keyword(s):  
Text Structure ◽  
Vibrational Amplitude ◽  
Low Energy Electron Diffraction ◽  
Hollow Structures ◽  
Parallel Component ◽  
Text Structures ◽  
Dependent Change ◽  
Low Energy Electron ◽  
Perpendicular Component ◽  
Chemisorption Bond

The adsorption geometries for the primitive (3×3), (2×2) and ([Formula: see text] structures of K, Rb and Cs on Ag(111) have been determined using low-energy electron diffraction. In the lower-coverage (3×3) and (2×2) structures, the adatoms occupy fcc hollow sites, while in the [Formula: see text]; structure they occupy the hcp hollow sites. The fcc hollow structures are accompanied by significant substrate rumpling. There is no significant coverage-dependent or site-dependent change in chemisorption bond length. However, there is a large coverage-dependent anisotropy of vibrational amplitude of the adatoms, with the parallel component as much as five times larger than the perpendicular component at low coverages.

STRUCTURE OF A SINGLE-ATOMIC LAYER OF COBALT ON THE Pt(111) SURFACE: A STUDY BY QUANTITATIVE LOW-ENERGY ELECTRON DIFFRACTION

1995 ◽  
Vol 02 (03) ◽  
pp. 279-283 ◽  
Author(s):  
ANDREA ATREI ◽  
MONICA GALEOTTI ◽  
UGO BARDI ◽  
MARCO TORRINI ◽  
ERMANNO ZANAZZI ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Atomic Structure ◽  
Room Temperature ◽  
Atomic Layer ◽  
Crystallographic Analysis ◽  
Low Energy ◽  
Energy Electron ◽  
Low Energy Electron Diffraction ◽  
Low Energy Electron

The atomic structure of the surface formed by depositing a single-atomic layer of cobalt on Pt (111) has been investigated using low-energy electron diffraction (LEED) crystallographic analysis. Cobalt grows at room temperature on the Pt (111) surface forming islands a single-atomic layer thick. The layer is ordered and it forms a 1×1 epitaxial phase where cobalt atoms are in an fcc registry with respect to the substrate.

THE ATOMIC STRUCTURE OF Si(111)-$(\sqrt{3}\times\sqrt{3})$R30°-Ga DETERMINED BY AUTOMATED TENSOR LEED

2000 ◽  
Vol 07 (03) ◽  
pp. 267-270 ◽  
Author(s):  
WENHUA CHEN ◽  
HUASHENG WU ◽  
WING KIN HO ◽  
B. C. DENG ◽  
GENG XU ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Atomic Structure ◽  
Atomic Layer ◽  
Low Energy ◽  
Wide Energy Range ◽  
Low Energy Electron Diffraction ◽  
Wide Energy ◽  
Low Energy Electron ◽  
Vertical Spacing ◽  
Iv Curves

The atomic structure of the Si (111)-[Formula: see text]R30°-Ga surface has been studied by comparing measured low-energy electron diffraction (LEED) intensity (IV) curves with calculated IV spectra using the method of automated tensor LEED. The experimental LEED IV curves used in this work contain many beams and a wide energy range. The results show that the Ga atoms occupy T4 sites, at 2.62 Å above the second-atomic-layer Si atoms. The Ga–Si vertical spacing is 1.44 Å and the bond length between the Ga atom and the first-layer Si atom is 2.52 Å. Large bucklings are found in the first and second Si bilayers below the adatom layer.

ATOMIC STRUCTURE OF A {001} SURFACE OF THE ALLOY FeRh

1999 ◽  
Vol 06 (01) ◽  
pp. 133-136 ◽  
Author(s):  
S. KIM ◽  
F. JONA ◽  
P. M. MARCUS
Keyword(s):  
Electron Diffraction ◽  
Surface Structure ◽  
Atomic Structure ◽  
Atomic Layer ◽  
Interlayer Spacing ◽  
Low Energy ◽  
Low Energy Electron Diffraction ◽  
Cscl Type ◽  
Low Energy Electron ◽  
Bulk Structure

The atomic structure of a {001} surface of the ordered binary alloy FeRh (with bulk structure of the CsCl type) is studied with quantitative low energy electron diffraction. The {001} surface structure is found to be bulklike (1× 1), with the first atomic layer 100% Rh and the second 100% Fe. The first interlayer spacing is contracted by 9.8% with respect to the bulk value (1.4935Å) and the second interlayer spacing is slightly expanded by 2.4%.

LEED INVESTIGATION OF THE Pb AND Sb ULTRATHIN LAYERS DEPOSITED ON THE Ni(111) FACE AT T=150–900 K

2003 ◽  
Vol 10 (06) ◽  
pp. 843-848 ◽  
Author(s):  
A. KRUPSKI ◽  
S. MRÓZ
Keyword(s):  
Electron Diffraction ◽  
Substrate Temperature ◽  
Atomic Structure ◽  
Ultrahigh Vacuum ◽  
Low Energy ◽  
Low Energy Electron Diffraction ◽  
Text Structures ◽  
Ultrathin Layers ◽  
Low Energy Electron ◽  
Good Agreement

The atomic structure of ultrathin lead and antimony layers deposited on the Ni (111) face in ultrahigh vacuum at a substrate temperature ranging from 150 to 900 K was investigated with the use of low-energy electron diffraction (LEED). LEED patterns corresponding to p(1×1), p(3×3), p(4×4), [Formula: see text] structures and p(1×1), p(2×2), [Formula: see text], [Formula: see text] structures for the adsorption of Pb and Sb, respectively, on the Ni (111) face were observed. Experimental LEED intensity-versus-energy [I(V)] spectra have been collected for the clean Ni (111) and for the [Formula: see text], [Formula: see text], [Formula: see text] structures. The I(V) curves obtained for the clean Ni (111) structure are in good agreement with experimental spectra from the literature.

STRUCTURE AND THERMAL STABILITY OF THE SULFIDE OVERLAYERS ON CH3CSNH2-PASSIVATED GaAs(100) SURFACES

2001 ◽  
Vol 08 (01n02) ◽  
pp. 19-23 ◽  
Author(s):  
F. Q. XU ◽  
E. D. LU ◽  
H. B. PAN ◽  
C. K. XIE ◽  
P. S. XU ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Electron Spectroscopy ◽  
Photoemission Spectroscopy ◽  
Low Energy Electron Diffraction ◽  
Native Oxides ◽  
Sulfur Passivation ◽  
Different Temperatures ◽  
Low Energy Electron ◽  
Synchrotron Radiation Photoemission ◽  
Thermal Stability Of

Chemically sulfur passivation of GaAs(100) by thioacetamide ( CH 3 CSNH 2) has been studied using synchrotron radiation photoemission spectroscopy (SRPES), Auger electron spectroscopy (AES) and low energy electron diffraction (LEED). The measurement of SRPES and AES showed that the top layer of native oxides over GaAs(100) was removed and the sulfides of Ga and As were formed after the passivation process. The thermal stability and surface structure have also been studied by annealing the passivated samples at different temperatures. We found that the surface sulfides could be removed gradually; as a result, a clean, ordered and thus Fermi level unpinning surface was finally achieved. The surface restructures with GaAs(100)–S(2×1) and 4×1 LEED patterns were observed on annealing above 260°C and at 550°C respectively.

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