Approaching the Zundel Limit: Tuning the Vibrational Coupling in N2H+Ng, Ng = {He, Ne, Ar, Kr, Xe, and Rn}

The diazenylium ion (N2H+) is a ubiquitous ion in dense molecular clouds. This ion is often used as a dense gas tracer in outer space. Most of the previous works on diazenylium ion have focused on the shared-proton stretch band,.H+. In this work, we have performed reduced-dimensional calculations to investigate the vibrational structure of N2H+Ng, Ng = {He, Ne, Ar, Kr, Xe, and Rn}. We demonstrate a few interesting things about this system. First, the vibrational coupling in N2H+ can be tuned to switch on interesting anharmonic effects such as Fermi resonance or combination bands by tagging it with different noble gases. Second, a comparison of the vibrational spectrum from N2H+He to N2H+Rn shows that the.H + can be swept from an Eigen-like to a Zundel-like limiting case. Anharmonic calculations were performed using a multilevel approach, which utilized the MP2 and CCSD(T) levels of theories. Binding energies for the elimination of Ng in N2H+Ng are also reported.

Automated summary

In this study, the vibrational structure of N2H+Ng (Ng = {He, Ne, Ar, Kr, Xe, and Rn}) was investigated using reduced-dimensional calculations. It was found that the vibrational coupling in N2H+ can be controlled by tagging it with different noble gases, resulting in interesting anharmonic effects such as Fermi resonance and combination bands. The comparison of the vibrational spectra revealed a transition of .H+ from an Eigen-like to a Zundel-like state. Additionally, the binding energies for the elimination of Ng in N2H+Ng were determined.