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Title: Applications of laser desorption laser photoionisation time-of-flight mass spectrometry
Author: Redpath, Craig Robertson
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1995
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This thesis describes the development and application of laser desorption laser photoinisation time-of-flight mass spectrometry (L2TOFMS) for the analysis of polymers and related systems. L2TOFMS has been little used in this area until now. In the past, this technique has been used extensively for the study of high mass, involatile and/or thermally labile species such as biomolecules, porphyrins and dyestuffs. The theory behind the main experimental principles is discussed and the equipment used is described in detail. The main body of the thesis is concerned with the generation of high quality polymer mass spectra. Utilising several ionisation wavelengths, the mass spectra of several aromatic polymers have been obtained for the first time. For two model polystyrene systems, polystyrene 800 and 2500, a series of intense oligomer peaks and some fragments were observed at each photoionisation wavelength employed. Fragments were shown to occur in the laser desorption event, a phenomenon previously documented. However, an intact oligomer series for these polymers had never previously been observed using this technique. The data obtained allowed a complete and unambiguous characterisation of the polystyrenes to be made. Molecular weight averages were calculated from the spectra. When 193 nm photoinisation was employed, these values compared favourably to those supplied by the manufacturer. However, photoinisation by either 248 nm or 266 nm UV radiation resulted in mass spectra which gave lower molecular weight averages. This was primarily due to oligomer fragmentation at these wavelengths. The analysis and characterisation of a fluorinated polystyrene and phenyl containing siloxane polymer was also carried out. L2TOF mass spectra were also recorded for several polymer additives in their pure form. Two compound classes of additive were studied, namely UV stabilisers and phenolic antioxidants.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available