Knowledge Bank

Rotational transitions of the $N2-CO$ van der Waals complex, including the $N2-13CO$ and $N2-13C18O$ isotopomers, were measured using a Fourier transform microwave spectrometer and a microwave-Terahertz double resonance spectrometer. It was possible to resolve and to assign the $\mathrm{<mrow\; data-mjx-texclass="ORD">14</mrow>}N$ nuclear hyperfine components of the rotational transitions. The spectral analyses yielded rotational, centrifugal distortion, and $\mathrm{<mrow\; data-mjx-texclass="ORD">14</mrow>}N$ nuclear quadrupole coupling constants. These results, in particular the nuclear quadrupole coupling constants, shed additional light onto the complex intermolecular dynamics of this very floppy system. We were able to access a new state that was not reported in the previous infrared $studies,a,b$ and will present a refined energy level diagram for the complex.