Negative Ion Resonances in the Fluorobenzenes and Biphenyl

Conclusion: In the present work a new experimental device was built, tested, and applied to the study of NIR's of a basic series of organic molecules. The importance of this work is threefold:

1. It has demonstrated that such a device can yield accurate values of electron affinities and vertical attachment energies.

2. A complete series of fluorine-substituted benzene derivatives has been studied to yield their electron affinities and/or vertical attachment energies. This has provided new insights concerning the negative ion states of these molecules.

3. Solid samples (with sufficient vapor pressures) can be studied with the present device to measure their VAE's and/or EA's. Such a sample is biphenyl for which VAE's were measured which, in turn, yielded information of the interaction of the two benzene rings.

Although negative ion resonances of benzene and the fluorobenzenes exist for very short lifetimes in isolated molecule conditions (i.e. the present work), their existence in condensed systems (eg. biosystems) is of fundamental importance in radiation damage. During low-energy electron interactions, these molecules can undergo inelastic resonance scattering whereby the molecule is left in a vibrationally excited state. The lifetime of this state can be sufficiently long to allow for chemical (biochemical) reactions.