Mass-Spectrometric Study of Ion—Molecule Reactions in Propane

Abstract

Ion—molecule reactions in propane have been studied up to pressure of 0.12 Torr inside the ion source of the mass spectrometer. All but four of the propane ions followed the exponential decay law remarkably well and their total cross sections of disappearance have been determined. The major reactions of these ions lead to the formation of C3H8+, C3H7+, C3H6+, and C3H5+ which, with the exception of C3H5, show very low reactivity. The ionic current due to purely secondary ions did not exceed few percent of the total ionic current at the highest pressure attained. The kinetics of most of the ion—molecule reactions occurring in propane have been investigated, and the pertinent cross sections have been determined.