Detection of the bending vibration of the CO–orthoN2 complex

The bending vibration of the CO–N 2 complex has been investigated in the millimeter wave range from 130 to 155 GHz using an intracavity OROTRON jet spectrometer. Six transitions, P (2), P (1), R (0), R (1), R (2), and R (3) from the K =0 ground state to the K =0 bending state of the ortho N 2 spin modification were measured and analyzed. Nuclear quadrupole structure due to the presence of two equivalent 14 N nuclei was partly resolved and analyzed to give information about the angular anisotropy of the interaction potential. The frequency of the bending vibration was determined to be 139892.459(35) MHz. The nuclear quadrupole coupling constant for the K =0 bending state of CO– ortho N 2 was obtained for the first time to be χ aa =−0.768(43) MHz . The different value and sign of this constant from the one in the K =0 ground state, (χ aa =+0.19641 MHz ) suggests that the orientation and motion of the N 2 subunit are very different in these two states.