A detailed description is given of an ion beam system and instrumentation used in studies of the ejection of electrons associated with the Auger neutralization of N2+, H2+, and N+ions in the energy range 10–30 eV under controlled surface conditions. Ions are generated in a low pressure discharge, electrostatically focused and mass analyzed by a refocusing magnetic spectrometer to remove undesired ion, neutral, and metastable species. The ion kinetic energy spread is low (approximately 0.4 eV at half‐maximum) and the beam intensity is as high as 10−8A. The combination of ultrahigh vacuum techniques to lengthen the time required to reach adsorption equilibrium after flashing, and special guarding and analog data reduction techniques to reduce instrumentation time response, permitted the study of transient adsorption effects as well as the more usual equilibrium studies.