Direct measurement of supra-thermal energy distribution of fragments following electron-impact ionization of molecules

Abstract

The energy distribution function of the molecular fragments produced by electron impact is measured using a combination of a delayed pulse extraction, a free-fall degradation of the ionic density along the beam path, and a time-of-flight spectroscopy. This new technique is able to measure energy distribution of ions from thermal energies up to few electron volts and allows measuring the energy distribution of singly charged ions which is difficult to obtain through the more usual method using the increase of the width of the peaks in the time-of-flight spectrum.