| Summary: | (e,2e) spectroscopy is a versatile tool to investigate the collision dynamics taking place in electron impact ionisation of atoms and molecules as it employs a kinematically complete view of the scattering process. (e,2e) measurements on He and H2 have been carried out from the coplanar to the perpendicular geometry at various impact energies, and these results are compared and discussed. Results for the atomic targets He, Ar and Xe and the molecular targets H2, N2 and CO2 are also presented from measurements in the perpendicular geometry and these are compared. The Ib1 molecular orbital of H20 has been studied at low to intermediate energies in a coplanar symmetric and asymmetric geometry. Where available the experimental data have been compared to theoretical calculations of other research groups located in the USA. A new coincidence spectrometer has been designed, assembled and commissioned which incorporates a pulsed, supersonic beam expansion as well as a continuous, effusive beam expansion. Measurements using supersonically expanded He and H2 demonstrated the feasibility of the new coincidence spectrometer for (e,2e) studies. The supersonic gas expansion provides molecular targets in their ground ro-vibrational states. This spectrometer allows the first steps towards the development of molecular alignment within the target beam. The alignment of diatomic molecules in the experiments would open up a new range of (e,2e) measurements with far-reaching implications for the investigation of collision dynamics from molecules.
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