Use this URL to cite or link to this record in EThOS:
Title: The development of ESEM and its application to food systems
Author: Bache, I. C.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 1999
Availability of Full Text:
Full text unavailable from EThOS.
Please contact the current institution’s library for further details.
The Environmental Scanning Electron Microscope (ESEM) is a new form of Scanning Electron Microscope (SEM) which supports a gaseous atmosphere and the presence of liquid water in the sample chamber. This opens up new possibilities for the use of ESEM to study many biological and food based systems which previously could not be satisfactorily studied using SEM. This thesis describes work carried out to understand the interactions between electrons and the water vapour present in the sample chamber, and examples of the use of ESEM to study two food based systems. The presence of gas in the chamber necessitates the use of a different type of electron detector than that used in conventional SEM. This detector utilises the gas in the chamber to amplify the electron signal. Previous descriptions of this amplification system have been found to be inadequate. A computer model was developed to simulate the behaviour of electrons as they are amplified through the gas, and an improved model suggested. The computer model was then applied to two other areas of electron interactions which were previously poorly described: the interactions of the high energy beam electrons with the gas, and the interactions of the signal electrons with condensed water. To illustrate the usefulness of the ESEM in studying food based systems, two examples were studied in detail. The gluten component of bread dough has interesting visco-elastic properties, and an attempt to study the development of its structure using ESEM was made. The mixture of gelatin and dextran in aqueous solution undergoes phase separation and gelation on cooling, and its final structure was studied using ESEM, as an example of a system that cannot be examined using conventional SEM.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available