High resolution electron interaction studies with atoms, molecules, biomolecules and clusters

lonisation and attachment by electrons are two of the most fundamental inelastic electron collision processes. Electron-impact ionisation/attachment processes are also important in many practical applications such as low-temperature plasma processing, fusion edge plasmas, planetary atmospheres, radiation chemistry and chemical analysis. Considerable progress in the experimental and theoretical description of electron-driven ionisation and attachment processes involving atomic and molecular targets has been achieved in the past decade, for instance concerning the quantitative determination of total and partial electron impact ionisation cross sections. Nevertheless, with respect to information about the finer details of this interaction, which has to come primarily from experimental studies, little is known due to the fact that experiments require the availability of electron beams of high quality in terms of electron energy resolution and accuracy. The very recent development, refinement and application of new experimental techniques in our laboratories (novel types of molecular beam sources and high resolution electron beam and mass spectrometry techniques, e.g., HEM-QM and TEM-QM allowing us to achieve in both routinely electron energy resolutions of about 30 to 50 meV at electron currents in the nA range, which are still high enough to carry out statistically relevant measurements for systems with low interaction cross sections) made this the ideal time for carrying out a coordinated series of experiments planned to attack the many open questions in this field. In this review we will first discuss the experimental set-up and techniques and then present some prototypical examples including (i) the determination of appearance energies and Wannier exponents for multiple ionisation of rare gases, (ii) isotope effects in the electron impact ionisation of H(2)/D(2) and H(2)O/D(2)O, (iii) appearance energy, binding energy and structure of the ozone dimer and finally (iv) vibrational structure in the dissociative electron attachment to formic acid.