Simpson, Matthew James
(2010).
Ion-molecule reaction mass spectrometry and vacuum-ultraviolet negative photoion spectroscopy.
University of Birmingham.
Ph.D.
Abstract
Two separate experimental techniques have been used to investigate the fundamental properties of small polyatomic molecules in the gas phase. Selected ion flow tube mass spectrometry has been used to study the reactions of cations and anions with ethene, monofluoroethene, 1,1-difluoroethene, trifluoroethene and tetrafluoroethene. Calculated collisional reaction rate coefficients are compared to those measured by the experiment. The product ions from these reactions have been detected and their branching ratios measured. Many of these results have been explained using arrow-pushing mechanisms. Using tunable vacuum-ultraviolet radiation from a synchrotron, negative ions have been detected following photoexcitation of 24 gaseous molecules. The majority of the molecules studied are halogen-substituted methanes. Product anions resulting from unimolecular ion-pair dissociation reactions were detected, and their ion yields recorded in the range 8-35 eV. Absolute cross sections for ion-pair formation and resulting quantum yields are calculated. This vast collection of data is summarised and ion-pair formation from polyatomic molecules is reviewed.
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