An evaluation of the role of internal energy and translational energy in the endothermic proton transfer reaction of N2H+ with Kr

Abstract

The Innsbruck SIDT (selected ion drift tube), now modified to include an octupole guided beam region, has been utilized to investigate the title reaction using both virbationally excited and ground state N₂H⁺. Rate constants measured for three distinguishable proton transfers at a field strength of 40 Td are 1.1×10⁻⁹, 2.7×10⁻¹⁰, and 1.3×10⁻¹¹ cm³ s⁻¹. These are assigned to the exothermic proton transfer reaction N₂H⁺ (X,v=2)+Kr→KrH⁺+N₂ and the endothermic reactions of N₂H⁺ (X,v=1) and N₂H⁺ (X,v=0), respectively. This assignment is supported by studies of the kinetic energy dependence of the rate coefficients and the collisonal relaxation of excited N₂H⁺ ions with N₂. The latter process is characterized by a large rate coefficient k_r=3×10⁻¹⁰ cm³ s⁻¹ approximately one‐third the collision rate coefficient.