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Abstract

A rovibrational relaxation model based on existing levels and transition probabilities for H₃⁺ is presented. In this model allH₃⁺ levels below 12000 cm^-1 and their respective transitions are included. The results are compared to Coulomb explosion measurements of the relaxation time of the first vibrational breathing mode and found to yield excellent agreement. Furthermore, the existence of long-lived rotational states with energies up to 1 eV, as detected in DR imaging experiments at the TSR storage ring, is backed by the model. A reduced set of differential equations-including only states below 8000 cm^-1 -was set up, which incorporates also induced transitions. This model was used to investigate the heating of subthermal ensembles of H₃⁺ ions exposed to 300 K blackbody radiation.