Reactions of thermal energy ions. VI. Hydrogen-transfer ion–molecule reactions involving polar molecules

The rate constants for formation of the protonated molecule by ion–molecule reactions in CH3OH, (CH3)2O, and CH4 have been studied both at thermal energies and at 3.4 eV ion exit energy with a new mass spectrometer described in the present work. The rate constants are found to be approximately a factor of two greater than previously measured and it is concluded that an error in pressure measurement was made in the earlier work. Revised rate constants are presented for a number of systems studied previously. The results are compared with predictions of the collision theory modified in this paper to include the effect of ion-dipole interactions.

REACTIONS OF THERMAL ENERGY IONS: II. RATES OF SOME HYDROGEN TRANSFER ION–MOLECULE REACTIONS

The rate constants for the ion–molecule reactions forming the protonated molecule in CH3CN, H2, CH4, and CH3OCH3, the equivalent reactions in the deuteriated species, and the reactions forming COD+ in CO–CD4 mixtures have been measured at thermal energies and at 10.5 V/cm repeller field strength. For H2, HD, D2 and the reactions in CO–CD4 mixtures the rate constant for the thermal reaction is approximately 0.3–0.5 that of the 10.5 V/cm rate constant. For all other cases the ratio of rate constants is approximately unity as predicted by the ion-induced dipole model. The absolute values of the rate constants in most cases are considerably lower than predicted by theory.