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Title: Harnessing a hybrid microscopy : vertically oriented probes in a scattered evanescent wave detection system
Author: Harniman, Robert
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2013
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Through the application of vertically oriented probes (VOPs) in a scattering evanescent wave (SEW) detection system the molecular resolution of SPM has been returned to the high temporal resolution, non-invasive regime of its optical microscopy forebear. The potential for VOP miniaturisation in the SEW system has been investigated using silvergallium needles and specifically designed, high-sensitivity cantilevers. These have spring constants as low 0.007 N/m and resonance frequencies up to 918 kHz in ambient conditions and 197 kHz in water. An optical feedback mechanism creates a hybrid microscopy, which presents a scanning plane at constant separation from the sample substrate with sub-nanometre precision in the vertical axis. Utilising this hybrid microscopy and high-sensitivity cantilevers, scan rates up to 8 frames per second in liquid environments were attained and lambda-DNA weakly bound to a mica substrate was resolved. The optical control presented is predicted to have a wide application in the measurement of surface and sample forces at the nano-scale. Indeed, it has already become the standard operating mode of all VOP experimentation within the Nano science group of Bristol University, due to its high degree of vertical control. Hybrid microscopy has answered questions about the formation and structure of self assembled cage-like structures (SAGEs), which had not been answerable by other microscopies currently available. The size of SAGEs formed in situ is characterized, their hollow structure confirmed and most dramatically, a predicted hexagonal ultra-structure of the particles is resolved in their natural liquid formation environment.
Supervisor: Miles, Mervyn Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available