Appearance Potentials as Obtained with an Analytical Mass Spectrometer

Abstract

A method is presented for measuring appearance potentials with an analytical mass spectrometer. Slight modifications of the ion source and a unique method of interpreting ionization efficiency curves produce values which are generally accurate to within 0 5 per cent. Electron energy in the bombarding beam is partially controlled by a grid The differential ion current due to a small change in ionizing potential is recorded and the interpretation produces efficiency curves which approach the form which could be obtained with mono-energetic electrons Conventional use of the instrument is not affected by the modification Bond-strengths determined from data by this method are in good agreement with published data