ABSOLUTE PARTIAL AND TOTAL ELECTRON-IMPACT IONIZATION CROSS-SECTIONS FOR C2H6 FROM THRESHOLD UP TO 950 EV

Electron impact ionization of ethane (C2H6) was studied with a modified Nier type ion source and a double focussing mass spectrometer (reversed geometry). Using the ion-beam-deflection-technique and a SIMION based correction procedure it is possible to determine accurately parent and fragment ion currents produced. This allows the determination of relative partial ionization cross section functions from threshold up to 950 eV for the production of C2H6+, C2H5+, C2H4+, C2H3+, C2H2+, C2H+, C-2(+); CH3+, CH2+, CH+, C+; C2H52+ and C2H32+, respectively. Absolute partial ionization cross section functions for these ions were obtained by charge-weighted summing of all the observed partial ionization cross sections and by normalizing to the absolute total ionization cross section at 100 eV reported recently by Djuric et al. [N. Djuric, I. Cadet and M. Kurepa, Int. J. Mass Spectrom. Ion Processes 108 (1991) Pi]. Comparisons are made to earlier measurements.