ELECTRON-ION COINCIDENCE EXPERIMENTS - ABSOLUTE DETECTOR EFFICIENCIESAND NEUTRAL DISSOCIATION CROSS-SECTIONS

Electron-ion coincidence studies, using 40 eV electrons on He, Ar, Kr, and N-2 and 30 eV electrons on CF4 have been carried out for all ions produced by impact of electrons on an effusive gas jet and electrons scattered through an angle of 45 degrees. The original purpose of thes e experiments was to obtain the absolute instrumental efficiency for o ur time-of-flight mass spectrometer. We have discovered, as a by-produ ct, that useful information about the absolute cross section for neutr al dissociation can also be obtained from such studies.