Knowledge Bank

A new absorption spectrum, attributed to the CCN radical, has been discovered in the flash photolysis of diazoacetonitrile $HC(CN)N2$; three electronic transitions between 3500 {\AA} and 4700 {\AA} have been observed. Rotational analyses of bands of these transitions have shown that the ground state of the radical is a $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}H2$ electronic state, and that the three observed excited states are $A2\Delta ,B2\Sigma -$ and $C2\Sigma +$. Analysis of sequence bands of the bending vibration indicates that the Renner-Teller interaction between the vibrational and electronic and electronic angular momenta in both the $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}H$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Delta$ electronic states is considerable; this interaction has not previously been observed for $^{2}\Delta $ states.