Low-lying bending vibronic bands of the MgNC ÃΠ2−X̃Σ+2 transition

We have generated MgNC in supersonic free jet expansions and measured the laser induced fluorescence excitation spectra of the Mg–N–C bending vibronic bands of the AΠ2−XΣ+2 transition. In addition to the two vibronic bands, 201, κΣ(+)2- and 202, κΠ2−Σ+2, reported previously, the 202, μΠ1∕22−Σ+2 vibronic subband was found just above the 201 band. The most remarkable feature of this subband is unexpected rotational structure of the A (020) μΠ1∕22 level, showing the splitting of the e and f sublevels. On the basis of the fact that the A (020) μΠ1∕22 level lies very close to the A (010) κΣ(+)2 level, the e∕f splitting is ascribed to P-type doubling which is induced by Coriolis interaction between these two bending vibronic levels. Introducing the Coriolis coupling terms arising from the G-uncoupling operator, −J±G22∓, and the spin-Coriolis interaction, S±G22∓, into the rotational Hamiltonian, this unexpected rotational structure has been analyzed. This P-type doubling would be one of the rare examples ex...