Structure and dynamics of N-2-IH

The ground state rotational spectra and internal dynamics in five isotopome rs N-14(2)-IH, N-14(2)-ID, N-15(2)-IH, (NN)-N-14-N-15-IH, and (NN)-N-15-N-1 4-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 spectroscopi c constants are interpreted in terms of a ground-state NN-IH structure usin g the parameters r(cm), k(sigma), and the oscillation angles theta(N2) and theta(HI) of the N-2 and IH moieties. For N-14(2)-IH, the values r(cm)=4.19 7 872(67) Angstrom, k(sigma)=1.461 52(32) N/m, theta(N2)=25.61(22)degrees, and theta(HI)=23.454 6(91)degrees are obtained. The rotational transitions of N-14(2)-IH, N-14(2)-ID, and N-15(2)-IH show a doubling, which is a conse quence of tunneling associated with the interchange of the two nitrogen nuc lei. The experimental findings are compared with results from ab initio cal culations. (C) 2000 American Institute of Physics. [S0021-9606(00)02024-9].