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Title: Nanoscale surface modification studied by reflection anisotropy spectroscopy
Author: Lane, Paul David
ISNI:       0000 0004 2731 1925
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2009
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The development and control of nanoscale properties is a major goal in science and technology; for the development of such technologies it is important that there are experimental techniques which allow the monitoring of development processes in real time and in a range of environments. With this in mind much effort has been invested in the development of surface sensitive optical probes. One such technique, reflection anisotropy spectroscopy (RAS), has been applied successfully to a number of different problems since its development in the mid 1980’s. RAS as a surface specific technique is very sensitive to small changes to surface morphology, electronic structure and molecular orientation. This makes RAS a useful technique to study nanoscale changes occurring at surfaces and it is applied here to three such systems, in an attempt to develop a better understanding of both the systems and the technique. Surface defects arising from thermal processing and etching of the sample are considered and are found to have a significant effect on both the electronic structure and the morphology of the surface. The time and temperature dependences of the RAS signatures allow the monitoring of surface dynamic processes. The deposition of a monolayer of adsorbate molecules onto the surface allows a new interface to be created. Monitoring the evolution of this surface during deposition provides information about both the substrate surface and the adsorba te covered surface; a theoretical framework has been outlined to show how the sources of anisotropy from multiple thin film layers combine to give a RAS signal. Azimuth dependent RAS (ADRAS) is known to provide information on surface symmetry and can be used to determine molecular orientation. There are also a number of other angles which affect the RA spectrum from a sample. A tilted molecule causes a breakdown in surface symmetry; this work shows how such an effect can be observed.
Supervisor: Cole, Jamie. ; Blackford, Jane. Sponsor: Engineering and Physical Sciences Research Council (EPSRC)
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: nanoscale ; surface sensitive optical probes ; reflection anisotropy spectroscopy ; nanoscale changes ; thermal processing ; surface defects ; surface symmetry ; Azimuth dependent RAS