Rovibrational Characterization and Interstellar Implications of the Proton-Bound, Noble Gas Complexes: ArHAr+, NeHNe+, and ArHNe+

The detection of the noble gas molecule ArH+ initially in the Crab nebula and elsewhere since has reinvigorated the search for naturally occurring, noble gas compounds. Additionally, proton-bound complexes are known to possess exceptionally bright vibrational modes corresponding to the shifting of the proton between the two, more massive moieties. As such, smaller column densities are required for unique detection of molecules with such intense transitions. In light of this, vibrational, rotational, and rovibrational spectroscopic data are provided here for ArHAr+, NeHNe+, and ArHNe+ to assist in laboratory characterization or even astronomical detection of these noble gas molecular cations. NeHNe+ is shown to be a surprisingly well-bound system, while the neon atom is not nearly as tightly bound to ArHNe+ in comparison. Furthermore, the reaction of the astronomically detected argonium cation with the strongly supported, potential interstellar ArH3+ cation will produce ArHAr+ with favorable energetics. This coupled with the fact that the proton shuttle fundamental has the largest intensity and lowest frequency in ArHAr+ of the three cations examined supports the idea that ArHAr+ is likely observable through either its vibrational mode or the rotations of this vibrationally excited state.