Ion- and Electron-induced Electron Emission

This project concerns construction and first applications of a novel experimental setup for measuring the momentum vectors of electrons ejected from well-defined solid surfaces in UHV due to the impact of energetic electrons or ions ("momentum vector spectroscopy - MOVES"). Single primary particles are applied in short pulses of about 1 ns duration in order to permit coincidence measurements with the thereby ejected electrons which will be guided from the target surface by a weak homogeneous magnetic field towards a position-sensitive detector. As compared to conventional electron spectroscopies, MOVES is able to cover electron emission into the complete hemisphere above the target surface, delivers both angular- and energy-dispersive data and permits, due to multihit-capability of the position-sensitive electron detector, correlation measurements between different ejected electrons. It has been shown by means of model calculations that both the energy-- and angular resolution of the proposed MOVES apparatus and the achievable coincidence rates will be sufficiently high to permit the above mentioned studies. The application of MOVES should deliver pertinent experimental data of high quality and thereby greatly improve our theoretical understanding of basically interesting and practically important phenomena such as secondary electron emission (SEE), ion-induced potential (PE) and - kinetic emission (KE), and the recently observed excitation of bulk- and surface plasmons due to potential ion energy ("potential excitation of plasmons - PEP"). In addition, such studies will be possible with very low primary particle fluxes which leave the status of the investigated surfaces practically unchanged during experimental runs.