Surface and interface structural studies using medium energy ion scattering
Sheppard, Daniel Crispin (2010) Surface and interface structural studies using medium energy ion scattering. PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b2486840~S15
The technique of medium energy ion scattering (MEIS) can be used to elucidate
the structural details of surfaces, both in general terms and in a more qualitative manner,
in order to help solve a number of outstanding uncertainties relating to the structures of
a number of surface systems. MEIS, involving the back-scattering of light ions from a
material of interest, in this case 100 keV H+ ions from adsorbate covered single crystal
metal surfaces, can potentially be a powerful tool for obtaining either depth-dependent
compositional information or quantitative structural details.
MEIS has been used to study the surface relaxations at the Cu(410)-O stepped
surface. The results have been compared to a number of models favoured by previous
studies, and an optimisation of the structural parameters associated with the outermost
Cu atoms was undertaken so as to determine the positions of these atoms to a reasonable
degree of precision.
In this thesis, MEIS has also been used to probe the surface reconstructions
triggered by the adsorption of the methylthiolate species on the Cu(100), Au(111) and
Pd(111) surfaces. Methylthiolate is derived from the n-alkylthiol molecule methylth-
iol, the simplest molecule of a species which ubiquitously form so called self-assembled
monolayers (SAMs) on single crystal metal surfaces. In the case of Cu(100), our study
confirms the existence of a radial lateral distortion of the outermost Cu layer, and we
quantify this distortion. For Au(111), two competing structural models for the methylth-
iolate overlayer have been proposed, namely the Au-adatom-monothiolate (AAM) and
Au-adatom-dithiolate (AAD). MEIS has been used to compare these two models, and we
find in favour of the AAD model. Additionally, evidence has been found for a significant
reconstruction of the Pd(111) surface triggered by adsorption of methylthiolate.
We have carried out a MEIS investigation of the (3×2)-alaninate phase formed
by adsorption of the chiral molecule alanine on Cu(110). Evidence is found for a small
degree of lateral surface distortion.
|Item Type:||Thesis or Dissertation (PhD)|
|Subjects:||Q Science > QC Physics|
|Library of Congress Subject Headings (LCSH):||Ions -- Scattering, Copper -- Surfaces, Gold -- Surfaces, Palladium -- Surfaces|
|Official Date:||September 2010|
|Institution:||University of Warwick|
|Theses Department:||Department of Physics|
|Supervisor(s)/Advisor:||Woodruff, D. P.|
|Extent:||xv, 109 leaves : ill., charts|
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