The Resource Diffraction studies of structure and growth of films absorbed on the AG(111) surface, by Zhongming Wu

Diffraction studies of structure and growth of films absorbed on the AG(111) surface, by Zhongming Wu

Label
Diffraction studies of structure and growth of films absorbed on the AG(111) surface
Title
Diffraction studies of structure and growth of films absorbed on the AG(111) surface
Statement of responsibility
by Zhongming Wu
Title variation
Diffraction studies of adsorbed films
Creator
Subject
Language
eng
Summary
Synchrotron x-ray diffraction has been used to investigate the structure and growth of physisorbed films on the Ag(111) surface. For growth under quasiequilibrium conditions, the Xe/vacuum interface profile for a complete monolayer and bilayer is found to have a higher degree of structural perfection than for kinetically grown films. Analysis of the specular reflectivity at different coverages between one and four layers yields the fractional layer occupancies and the spacing between the Ag(111) surface and the first Xe layer. The number of partial layers increases with the coverage. The spacing between the Ag(111) surface and the first Xe layer is consistent with the results of previous studies within the experimental uncertainty. The film stacking sequence at an early growth stage is studied by integrated intensity measurements along the Xe (10l) rod for coverages of three and four layers. The model calculations indicate a fraction of 'ABA' stacking faults which decreases as the coverage increases. Studies of n-alkane films adsorbed on the Ag(111) surface demonstrate that the alkane monolayers grow with a well defined orientational relationship with the substrate apparently forming a higher-order commensurate structure. Butane and hexane monolayers have an oblique unit cell with two molecules in a herringbone arrangement. The oblique unit cell is derived from two monolayer in-plane peaks found by x-ray diffraction. For heptane, the monolayer structure on Ag(111) is consistent with the rectangular-centered structure as found on graphite. On growing from one to three layers at a temperature of 40 K, the butane film compresses and rotates by ${\sim}0.5\sp\circ$ in the direction away from the Ag(10) azimuth. Analysis of a scan along the butane (20) rod suggests a plausible bilayer structure simply related to that of the bulk. While butane film growth is preempted by bulk nucleation at $\sim$2.7 layers, the columnar bulk particles are quasiepitaxially oriented with a (100) plane parallel to the substrate surface at a fixed azimuthal orientation. A similar growth model is also observed for hexane and heptane films. We have conducted a series of low-energy electron diffraction (LEED) 'kinetic isotherm' experiments on hexane film adsorbed on the Ag(111) surface. The growth behavior falls into two categories. At low temperatures (40 K-120 K), the film growth is 'first-order'. At high temperatures (T $\geq$ 140 K), the kinetic isotherms exhibit three characteristic regions: a nearly exponential attenuation of the Ag(10) LEED spot intensity at early stage, an accelerated attenuation at intermediate times, and a leveling off in the attenuation as monolayer saturation is approached
Additional physical form
Also available on the Internet.
Cataloging source
MUU
http://library.link/vocab/creatorDate
1952-
http://library.link/vocab/creatorName
Wu, Zhongming
Degree
Ph. D.
Dissertation year
1997.
Government publication
government publication of a state province territory dependency etc
Granting institution
University of Missouri-Columbia
Illustrations
illustrations
Index
no index present
Literary form
non fiction
Nature of contents
  • bibliography
  • theses
http://library.link/vocab/subjectName
  • X-rays
  • Low energy electron diffraction
  • Surfaces (Physics)
  • Monomolecular films
  • Thin films, Multilayered
  • Liquid crystals
  • Silver
  • Xenon
  • Alkanes
Target audience
specialized
Label
Diffraction studies of structure and growth of films absorbed on the AG(111) surface, by Zhongming Wu
Instantiates
Publication
Note
  • Typescript
  • Vita
Bibliography note
Includes bibliographical references (leaves 197-202)
Carrier category
online resource
Carrier category code
  • cr
Carrier MARC source
rdacarrier
Content category
text
Content type code
  • txt
Content type MARC source
rdacontent
Control code
42471622
Dimensions
29 cm
Dimensions
unknown
Extent
xii, 263 leaves
Media category
computer
Media MARC source
rdamedia
Media type code
  • c
Other physical details
illustrations
Specific material designation
remote
Label
Diffraction studies of structure and growth of films absorbed on the AG(111) surface, by Zhongming Wu
Publication
Note
  • Typescript
  • Vita
Bibliography note
Includes bibliographical references (leaves 197-202)
Carrier category
online resource
Carrier category code
  • cr
Carrier MARC source
rdacarrier
Content category
text
Content type code
  • txt
Content type MARC source
rdacontent
Control code
42471622
Dimensions
29 cm
Dimensions
unknown
Extent
xii, 263 leaves
Media category
computer
Media MARC source
rdamedia
Media type code
  • c
Other physical details
illustrations
Specific material designation
remote

Library Locations

    • University of Missouri Libraries DepositoryBorrow it
      2908 Lemone Blvd, Columbia, MO, 65211, US
      38.919360 -92.291620
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