THE STUDY OF SURFACE SEGREGATION, STRUCTURE, AND VALENCE BAND DENSITY OF STATES OF Pt3Ni(100), (110), AND (111) CRYSTALS

2006 ◽  
Vol 13 (05) ◽  
pp. 697-702 ◽  
Author(s):  
B. S. MUN ◽  
M. WATANABE ◽  
M. ROSSI ◽  
V. STAMENKOVIC ◽  
N. M. MARKOVIC ◽  
...  
Keyword(s):  
Single Crystals ◽  
Valence Band ◽  
Density Of States ◽  
Surface Segregation ◽  
Low Energy ◽  
Ion Scattering ◽  
Low Energy Ion Scattering ◽  
Low Energy Electron ◽  
Valence Bands ◽  
Segregation Structure

The surface segregation, structure, and valence band density of states of Pt 3 Ni (100), (110), and (111) single crystals are characterized with low energy ion scattering (LEIS), low energy electron diffraction (LEED), and ultraviolet photoemission spectroscopy (UPS). The results of LEIS clearly reveal the complete surface segregation of Pt to the top layer on all crystal alloys. LEED indicates the (5 × 1) surface reconstruction on the Pt 3 Ni (100), while (110) and (111) surfaces show (2 × 1) and (1 × 1) patterns, respectively, identical to Pt single crystals. The valence bands density of states on Pt 3 Ni alloys are compared to those of Pt single crystals via UPS measurements.

Surface segregation of gold for Au/Pd(111) alloys measured by low-energy electron diffraction and low-energy ion scattering

2008 ◽  
Vol 602 (5) ◽  
pp. 1084-1091 ◽  
Author(s):  
Zhenjun Li ◽  
Octavio Furlong ◽  
Florencia Calaza ◽  
Luke Burkholder ◽  
Hin Cheuk Poon ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Surface Segregation ◽  
Low Energy ◽  
Energy Electron ◽  
Ion Scattering ◽  
Low Energy Electron Diffraction ◽  
Low Energy Ion Scattering ◽  
Low Energy Electron

Surface Characteristics Of Quasicrystalline Materials: An Overview Of Work Conducted At Ames Laboratory

1998 ◽  
Vol 553 ◽  
Author(s):  
C. J. Jenks
Keyword(s):  
Bulk Composition ◽  
Surface Characteristics ◽  
Low Energy ◽  
Ion Scattering ◽  
Low Energy Ion Scattering ◽  
Ames Laboratory ◽  
Temperature State ◽  
Higher Temperature ◽  
Low Energy Electron ◽  
Bulk Model

AbstractOver the last few years, work in our laboratories in Ames has focussed on elucidating the surface characteristics of Al-based quasicrystalline materials, namely icosahedral (i-) Al-Cu-Fe and i-Al-Pd-Mn. Our work involves the study of the clean surfaces of these materials under ultrahigh vacuum conditions. We find that surfaces cleaned by Ar+ sputtering are depleted in Al relative to the bulk composition. Single grains, after sputtering, undergo a two-stage regrowth process as they are annealed. After heating to about 600 K, a crystalline overlayer is formed. This is rather abruptly replaced at about 750 K by a surface that appears quasicrystalline within the resolution of the experimental techniques used. Calculations based on low-energy electron diffraction (LEED) measurements of this higher temperature state indicate that the Al-rich layers in the bulk model of these materials are the favored surface terminations. Results of low-energy ion scattering (LEIS) corroborate this finding. Consistent with this, we find that the oxidation behavior and general reactivity of these materials are analogous to pure Al.

THERMAL DESORPTION OF SODIUM ATOMS FROM THIN SiO2 Films

2000 ◽  
Vol 07 (01n02) ◽  
pp. 75-87 ◽  
Author(s):  
B. V. YAKSHINSKIY ◽  
T. E. MADEY ◽  
V. N. AGEEV
Keyword(s):  
Thermal Desorption ◽  
Photoelectron Spectroscopy ◽  
Low Energy ◽  
Ionic Character ◽  
Ion Scattering ◽  
Low Energy Electron Diffraction ◽  
Low Energy Ion Scattering ◽  
Low Energy Electron ◽  
Temperature Programmed ◽  
Substrate Temperatures

The adsorption and thermal desorption of Na from thin SiO2 films have been studied. X-ray photoelectron spectroscopy (XPS), angle-resolved XPS (ARXPS), low energy ion scattering (LEIS), temperature-programmed desorption (TPD), low energy electron diffraction (LEED) and work function measurements have been used to characterize the growth mechanism and properties of stoichiometric SiO2 films deposited onto a Re (0001) substrate. Upon deposition of Na onto SiO2 at 250 K, the first monolayer of Na exhibits ionic character, and evidence of metallic Na (plasmon features in XPS) is observed for higher coverages. TPD spectra for Na from SiO2 include a monolayer peak at ~700 K, and the multilayer peak due to sublimation of bulk Na at ~330 K. Penetration of Na into SiO2 can be induced by heating, or by He ion bombardment of a Na/SiO2 layer. The sticking probability for Na on SiO2 is ~0.5 at 250 K, and it decreases at higher substrate temperatures.

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