Rotational Dependence of the Proton Transfer Reaction HBr+ (N+) + CO2 → HOCO+ + Br

Abstract

Absolute cross sections and rate constants for the endothermic proton transfer reaction of rotationally state selected HBr+ ions with CO2 were measured as a function of the rotational energy for different center-of-mass (c.m.) collision energies. State selection of HBr+ ions was achieved via a (2+1) resonance enhanced multiphoton ionization (REMPI) process. By choosing different pump lines the mean rotational energy of HBr+ was varied from 1.6 to 25.9 meV. All experiments were performed in a linear ion guide apparatus. Collision energies considered ranged from 0.28 to 0.85 eV (c.m.). At the highest collision energies the cross section decreases by about 60% from 10 Å2 to 4 Å2 with increasing rotational energy. In contrast to that, at the lowest collision energies the cross section was about 2.5 Å2, independent of the rotational energy.