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Research Topics: Monolayer Characterisation

My group has always been actively involved in the development of new experimental techniques for characterising thin organic films at interfaces. For example, we reported the first sum-frequency spectra of a boundary lubricant at the solid–solid interface and of a surfactant at the alkane–water interface. We extended a suite of existing techniques, such as ELLIPSOMETRY, NEUTRON REFLECTION and FTIR SPECTROSCOPY, to flowing liquid surfaces using an overflowing cylinder or a liquid jet. We have shown theoretically that FTIR spectroscopy can distinguish surfactants at a surface from those in a bulk aqueous solution and demonstrated that, with the use of chemometrics, this distinction can be accomplished in practice. Recently, we have developed evanescent wave RAMAN SPECTROSCOPY for the study of surfactants and lipids at the solid–water interface.

Dynamic surface excess of the surfactant CTAB on an overflowing cylinder, determined by external reflection FTIR spectroscopy

An area of current interest is the structure and properties of biological surfactants at oil–water interface. To use ellipsometry as a structural technique, we are studying a number of model systems to help us to understand how to interpret ellipsometric data. We are also developing Raman spectroscopy for characterising the o–w interface, using thin oil films spin–coated on silica.