Two Studies in Gas-Phase Ion Spectroscopy

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.

Nominated by the University of Birmingham for a Springer Theses Prize.

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 .

This report covers two investigations into gas-phase ion spectroscopy; the first using tunable vacuum-ultraviolet radiation to identify negative ions from photoexcited polyatomic molecules, and the second studying ion flow tube mass spectrometry.