Structure and dynamics of N2–IH

The ground state rotational spectra and internal dynamics in five isotopomers N214–IH, N214–ID, N215–IH, N14N15–IH, and N15N14–IH of the nitrogen–hydrogen iodine dimer have been investigated by pulsed-nozzle, Fourier-transform microwave spectroscopy. Analysis of the recorded spectra yields rotational, centrifugal distortion, nuclear quadrupole and spin-rotation coupling constants for the five isotopomers. The spectroscopic constants are interpreted in terms of a ground-state NN–IH structure using the parameters rcm, kσ, and the oscillation angles θN2 and θHI of the N2 and IH moieties. For N214–IH, the values rcm=4.197 872(67) Å, kσ=1.461 52(32) N/m, θN2=25.61(22)°, and θHI=23.454 6(91)° are obtained. The rotational transitions of N214–IH, N214–ID, and N215–IH show a doubling, which is a consequence of tunneling associated with the interchange of the two nitrogen nuclei. The experimental findings are compared with results from ab initio calculations.