Reactions of excited and ground state H 3+ ions with simple hydrides and hydrocarbons: collisional deactivation of vibrationally excited H 3+ ions

Abstract

The reactions of H 3 + ions with CH 4, NH 3, H 2O, H 2S, C 2H 2, C 2H 4, and C 2H 6 are investigated using ion-cyclotron resonance methods. Except for the reaction H 3 +H 2O, the product distributions for these reactions are highly dependent on the amount of excess vibrational energy in H 3 + ions formed by the reaction H 2 + + H 2. Both the product distributions for the initial distribution of highly vibrationally excited H 3 + ions, and the product distributions for the ground state ions, are found by performing experiments as a function of H 2 pressure. The rate constant for the deactivation of the initial distribution of excited H 3 + ions to ground state ions in collisions with H 2 is found to be (2.7±0.6) × 10 −10 cm 3/sec. The rate constants for the reaction of H 3 + ions with the various molecules studied are shown to be independent of excess ion vibrational energy and to agree closely with values calculated using the average-dipole-orientation theory [11].