Knowledge Bank

The band of $NO3$ at $1492cm-1$ reported previously [J. Chem. Phys. 82, 2196 (1985)] has been reinvestigated by extending the observations so as to take ground-state combination differences. A slight revision of the assignment now removes all anomalies from the ground state. On the other hand, a small, but finite spin-orbit interaction term exists in the upper state. The first-order Coriolis coupling constant which was observed differs much from the calculated value. This and other anomalous features in the upper state are discussed in light of a few models including a dynamical $C2v$ structure.