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Low energy electron diffraction determination of the surface structures formed by the carbon monoxide chemisorption on the nickel(110) surface
Title
Low energy electron diffraction determination of the surface structures formed by the carbon monoxide chemisorption on the nickel(110) surface.
Creator
Zhao, Changyi, Florida Atlantic University, Passler, Mark A.
Abstract/Description
Low Energy Electron Diffraction is used to determine the different structures formed by the CO adsorption on the Ni(110) surface at two coverages. At full coverage the superlattice is Ni(110)-(2 x 1)2CO. For this superlattice, the CO molecules adsorb at the short bridge sites with a 20 degrees common tilt in the +-[001] directions. The Ni-C and the C-O bond lengths are 1.85 A and 1.15 A, respectively. In the Ni(110)-c(2 x 4)3CO superlattice structure, which is formed at an intermediate...
Show moreLow Energy Electron Diffraction is used to determine the different structures formed by the CO adsorption on the Ni(110) surface at two coverages. At full coverage the superlattice is Ni(110)-(2 x 1)2CO. For this superlattice, the CO molecules adsorb at the short bridge sites with a 20 degrees common tilt in the +-[001] directions. The Ni-C and the C-O bond lengths are 1.85 A and 1.15 A, respectively. In the Ni(110)-c(2 x 4)3CO superlattice structure, which is formed at an intermediate coverage, the CO molecules adsorb at the top sites with two types of configurations on alternate (110) rows. Half the rows are filled with CO molecules having a 9 degrees zig-zag common tilt in the $\pm$ (001) directions, and half the rows are half filled with untilted CO molecules. The Ni-C and the C-O bond lengths are 1.67 A and 1.15 A, respectively. The possible role of hydrogen in the formation of the surface structure is discussed.
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Date Issued
1993
PURL
http://purl.flvc.org/fcla/dt/14934
Subject Headings
Low energy electron diffraction, Surfaces (Physics), Surface chemistry, Chemisorption
Format
Document (PDF)
Low energy electron diffraction (LEED) determination of surface structure applied to nickel(110)-nitric oxide and to the martensitic alloy iron-33 percent nickel(111)
Title
Low energy electron diffraction (LEED) determination of surface structure applied to nickel(110)-nitric oxide and to the martensitic alloy iron-33 percent nickel(111).
Creator
Fan, Zeyuan, Florida Atlantic University, Passler, Mark A.
Abstract/Description
The purpose of this thesis is to provide a comprehensive overview of an important technique (low energy electron diffraction) used in the study of surface phenomena. Within this context, the LEED studies of NO adsorbed on the Ni(110) surface and of Fe-33%Ni(111) near its Martensitic transition temperature were done to determine their surface structures.
Date Issued
1991
PURL
http://purl.flvc.org/fcla/dt/14765
Subject Headings
Surfaces (Physics), Low energy electron diffraction, Surface chemistry
Format
Document (PDF)
Photoemission study of Shockley-type surface states on the (111) surfaces of copper-gold alloys
Title
Photoemission study of Shockley-type surface states on the (111) surfaces of copper-gold alloys.
Creator
Masliah, Lilian Regina, Florida Atlantic University, Jordan, Robin G.
Abstract/Description
Angle-resolved UV photoelectron spectroscopy has been used to investigate some of the properties of the occupied Shockley-type surface states that exist on the (111) surfaces of Cu, Au, ordered Cu3Au and ordered CuAuI. These states appear in normal and off-normal spectra near the Fermi level and their binding energies are independent of photon energy; however, the intensity of their emission relative to that of the d-bands is photon energy dependent, decreasing monotonically from ArI to NeI...
Show moreAngle-resolved UV photoelectron spectroscopy has been used to investigate some of the properties of the occupied Shockley-type surface states that exist on the (111) surfaces of Cu, Au, ordered Cu3Au and ordered CuAuI. These states appear in normal and off-normal spectra near the Fermi level and their binding energies are independent of photon energy; however, the intensity of their emission relative to that of the d-bands is photon energy dependent, decreasing monotonically from ArI to NeI to HeI. As the emission angle is increased from the normal, the states move towards and eventually cross the Fermi level, and we have measured this dispersion in k space. We show that the occupied extents of the dispersion relations, delta k, are related to features of the bulk band structures. For example, in Cu and Au the surface state follows the dispersion of the uppermost occupied band edge in the vicinity of the L-point and so the delta k extent is related to the (111) neck radius on the Fermi surface. Because the changes in the delta k extents are of the same order as the experimental uncertainty, we are unable to determine precisely how they vary with composition. We have fitted the dispersion data to 'free-electron' parabolas and calculated an effective electron mass in each case; we find that the effective masses in the alloys are somewhat larger than in the pure metals. The photoemission measurements described here on CuAuI(111) are the first ever to be taken on an alloy of that composition.
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Date Issued
1995
PURL
http://purl.flvc.org/fcla/dt/15221
Subject Headings
Photoemission, Photoelectron spectroscopy, Alloys, Surfaces (Physics)
Format
Document (PDF)
A Comparative Study on the Tensile Properties of Shark Skin
Title
A Comparative Study on the Tensile Properties of Shark Skin.
Creator
Creager, Shelby, Porter, Marianne C., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description
Our goal was to assess regional differences in denticle density and skin tensile properties in four coastal species of shark. We hypothesized that the denticle density, tensile strength (MPa), stiffness (MPa), and toughness of skin (MJ·m^-3) would vary regionally along the body of an individual and among species. An hourglass-shaped punch was used to extract the skin samples at 10 anatomical landmarks and denticle density was quantified. Denticle density varied significantly among both...
Show moreOur goal was to assess regional differences in denticle density and skin tensile properties in four coastal species of shark. We hypothesized that the denticle density, tensile strength (MPa), stiffness (MPa), and toughness of skin (MJ·m^-3) would vary regionally along the body of an individual and among species. An hourglass-shaped punch was used to extract the skin samples at 10 anatomical landmarks and denticle density was quantified. Denticle density varied significantly among both regions and species, and showed a significant species by region interaction. Skin samples were tested in tension at a strain rate of 2 mm-s until failure. We found significant species and region effects for all tensile and denticle density properties. Also, denticle density increases with skin stiffness but decreases with toughness. Shark skin toughness is similar to that of mammalian tendons. These data show shark skin functions as an exotendon, able to conserve energy during swimming.
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Date Issued
2016
PURL
http://purl.flvc.org/fau/fd/FA00004761, http://purl.flvc.org/fau/fd/FA00004761
Subject Headings
Sharks--Anatomy., Sharks--Locomotion., Surfaces (Physics), Biophysics.
Format
Document (PDF)