Knowledge Bank

The absorption spectrum in the region $3800-5000\backslash AA$ obtained in the flash photolysis of $HNF2$ has been photographed at high resolution. The conclusions of the earlier $workers1$ are confirmed, namely that it is due to HNF, which is bent in both ground and excited states. The band system consists of a single progression in the bending vibration $v2$, and there are prominent axis-switching'' effects due to the large change in bond angle. The $\rho$-type doubling is interpreted in terms of interaction between ground and excited states, which correlate with the two (Renner) components of a linear $^{2}II$ state. The $v_{2}{^{\prime}} = 1$ state shows evidence of second-order rotational resonance'' with the state.