Use this URL to cite or link to this record in EThOS:
Title: Atomic-scale imaging of adsorption, oxidation and co-adsorption on Ag{111}
Author: Carlisle, C.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2000
Availability of Full Text:
Full text unavailable from EThOS.
Please contact the current institution’s library for further details.
The work presented in this thesis draws upon several uses of STM, from structural determination, when used in conjunction with theoretical simulations, to the observation of surface reactions and surface mediated interactions. Simulations have been used here for the first time to allow the complete structural determination of a complex reconstruction. The determination of the reconstruction's structure and composition has enabled further experiments involving the oxidation of the Ag{111} surface as well as adsorbate-oxygen interactions mediated by the surface. The source of inspiration for these studies has been the catalytic epoxidation of ethene on silver by atomic oxygen. Two 'surface' states of atomic oxygen have been observed. The first, denoted Oc, is considered to adsorb in interstitial sites within the top layer of AG{111}. Its adsorbate-adsorbate repulsive nature sees this species rapidly saturating at a coverage of just 0.05 ML, at which point the p(4x4)-O species becomes more stable and its growth is nucleated at step edges. On decomposition of the p(4x4)-O reconstruction, both Ag{111} triangular islands and fractures within the oxide appear across the terraces. Both features may play a significant role in the catalytic behaviour. Ethene adsorption on clean Ag{111} has provided information on the adsorption geometry, adsorption state and appearance in the STM image allowing confident interpretations of the coadsorbed ethene-oxygen system. Tip pulsing has been used to provide a controlled mechanism for the induced transition from the physisorbed intrinsic precursor state of ethene to that of the chemisorbed state. High-resolution images have enabled the direct observation of Friedel surface oscillations surrounding the chemisorbed state. To my knowledge, this is the first direct observation of such oscillations resulting from adsorbates.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available