In this thesis Matthew Simpson reportstwo areas of work in gas ion spectroscopy, each investigation in itself worthy of a PhD. The first study uses tunable vacuum-ultraviolet radiation from a synchrotron to identify negative ions from twenty four photoexcited polyatomic molecules in the gas phase. From these experiments, Matthew collects a vast amount of data and summarises and reviews ion-pair formation from polyatomic molecules. The second study is on selected ion flow tube mass spectrometry. Matthew investigates the reactions of cations and anions with ethene, monofluoroethene, 1,1-difluoroethene and tetrafluoroethene. In this study Matthew tries to explain why certain products are formed preferentially over other products at a microscopic level of understanding. The data recorded in this thesis form the most comprehensive collection of information about anion formation and are the basis of a review and numerous articles in specialist journals.

Introduction and background information

The experiments
Vacuum-ultraviolet negative photoion spectroscopy of SF₆, CF₄ and SF₅CF₃
Vacuum-ultraviolet negative photoion spectroscopy of CF₃Cl, CF₃Br and CF₃I
Vacuum-ultraviolet negative photoion spectroscopy of SF₅Cl
Vacuum-ultraviolet negative photoion spectroscopy of small polyatomic molecules
The reactions of CF_n⁺ (n = 1-3) with C₂H₄, C₂H₃F, CH₂CF₂ and C₂HF₃
The reactions of C₂F₄⁺ with C₂H₄, C₂H₃F, CH₂CF₂ and C₂HF₃
Reactions of OH^-, O^-, CF₃^-, F^- and O₂^- with C₂H₄, C₂H₃F, CH₂CF₂, C₂HF₃ and C₂F₄ .