Knowledge Bank

The region $1370-1560cm-1$ contains two fundamental bands, the strong perpendicular band of the doubly degenerate $\nu 6$(species E) and the parallel band of the totally symmetric $(A1)$ vibration $nu3$. In addition, the $\nu 7+\nu 8$ and $\nu 4+2\nu 8$ combination states also occur in this region. The two fundamentals interact strongly by a first order $Jx,y$,-Coriolis coupling while the E component of $\nu 7+\nu 8$ is in Fermi resonance with $\nu 6$, and the $A1$ and $A2$ components of $\nu 7+\nu 8$ are in Fermi resonance with the $nu3$ fundamental. Also in evidence are an additional weaker anharmonic resonance of $\nu 6$ with the $\nu 4+2\nu 82$ combination, as well as x,y - Coriolis-type and second-order rotational interactions which couple the various states. The interactions are incorporated into a $9\times 9$ Hamiltonian matrix used for the upper states to adjust their spectroscopic constants yielding an overall standard deviation of the fit to all observed lined of $0.0015cm-1$. Spectroscopic parameters for all the states involved and for their interactions will be reported.