ABSOLUTE PARTIAL AND TOTAL ELECTRON-IMPACT IONIZATION CROSS-SECTIONS FOR C3H8 FROM THRESHOLD UP TO 950 EV

Electron impact ionization of propane (C3H8) was studied using the ion beam deflection technique and a double focussing mass spectrometer in conjunction with a recently developed correction procedure that accounts for discrimination due to the initial kinetic energy of fragment ions. The relative corrected partial ionization cross sections for the production of C3H8+, C3H7+, C3H6+, C3H5+, C3H4+, C3H3+, C3H2+, C3H+, C3+; C2H5+, C2H4+, C2H3+, C2H2+, C2H+, C2+; CH3+, CH2+, CH+, C+; C3H52+, C3H42+, C3H32+ and C3H22+ were determined from threshold up to 950 eV. Absolute partial ionization cross sections were obtained by charge weighted summing of all the observed partial ionization cross sections and by normalizing to a recent accurate determination of the total ionization cross section at 100 eV by Djuric et al. 1991. The absolute total ionization cross section curve obtained is in excellent agreement in shape and magnitude with the low energy data (< 200 eV) of Djuric et al. 1991 and the high energy data points of Schram et al. 1966.