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 CH 3 OH, (CH 3 ) 2 O, and CH 4 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.