Production of short ion pulses for TOF-RBS

Protons and 4He ions of 100 keV were scanned across a slit system by rapidly changing electric fields, whereby a small fraction of the incident ions passed the system forming short ion pulses. The energy shift and energy spread created by the electric fields as well as the effects of internal pulse compression were observed for the first time. Combining the short ion pulses with the time-of-flight (TOF) technique, Rutherford backscattering spectroscopy (RBS) of ultra-thin films can be performed with a depth resolution of better than 1 nm.