Ion–Molecule Reactions in Alpha-Particle Irradiated NH3, CD4, and D2O

Abstract

We have investigated the time evolution of the various primary and secondary positive ion species formed in NH3, CD4, and D2O gases bombarded by 1‐ to 3.5‐MeV alpha particles. The measurements were made with a pulsed time‐of‐flight mass spectrometer at pressures in the 10–40 micron range. Ion–molecule reaction schemes are proposed, the data analyzed for self‐consistency, and a variety of reaction rates deduced. Comparisons are made with other experiments in which electron bombardment was used for primary ionization. Our results indicate the existence of a relatively long‐lived [τ = 0.28(4)μ sec ] (C2D7 +)* ion complex formed from the reaction CD3 ++CD4, paralleling previous results [R. A. Fluegge, J. Chem. Phys. 50, 4373 (1969)] for the CH4 system.