Industrial applications of high resolution chemical mapping

Abstract

Working in a commercial research environment, the exploration of noveltechniques and adapting methods to the specific needs of the scientific projects running within the organisation, dictate an “out of the box” and creative approach using established techniques from other disciplines (e.g. biomedical and materials science). The company’s research projects demand high throughput speed combined with a “simple” but “all-inclusive” answer that correlates compositional information to microstructure from macroscopic down to the nanometre level.The motivation behind this PhD study was the desire to work out the key experimental and practical issues involved in designing and deploying a scanning electron microscope (SEM) combined with Raman spectroscopy, the so-called cryo In-SEM Raman system. This cryo In-SEM Raman instrument enables the retrieval of compositional information by Raman spectroscopy at a micrometer-resolution level from a frozen hydrated bulk specimens and correlate this to the observed micro-structure. The effects of cooling on the Raman spectra of model systems were studied. The application section of this thesis shows the added value of the combined technique by analysing the distribution of carotenoids in processed food emulsions. The significance of this combination of techniques is found in the installation of two cryo In-SEM Raman systems in 2011 in the Dutch academia. To produce optimal sample geometry for In-SEM Raman but also for analytical microscopy in general, sample preparation procedures were developed resulting in a grazing angle approach for the Focussed Ion Beam-SEM technique that significantly reduces analysis time while increasing the sample dimensions required for analytical add-ons to the scanning electron microscope. Low temperature resin embedding and cryo preparation methods for the preparation of open and brittle structures packed with organic solvents were developed enabling chemical mapping of the liquid phases of detergent particles by energy dispersive x-ray spectroscopy.

Thesis is embargoed until 31st January 2013

Date of Award	Jan 2011
Original language	English
Supervisor	Vyvyan Howard (Supervisor) & George Mc Kerr (Supervisor)