Knowledge Bank

3sc $\leftarrow 1\Pi$ The absorption spectrum of NO has been photographed in the 600 - 1000 {\AA} region with a 6.65 m VUV spectrograph in the second order. Vibrational isotope shifts $(N14O$, $N15O)$ indicate that the four bands at 829.38, 820.73, 812.65, and 304.80 {\AA} belong to a single $v\prime$ progression with $v\prime =1,2,3$, and 4, respectively. The upper electronic state should be the lowest member of the Rydberg series $\eta \leftarrow \ln 1$, with $\eta =3$, converging to the $W1\Delta$ state of $NO+$. The (3,0) band is well resolved and a rotational analysis yields $B3=1.27cm-1(r3=1.33\backslash AA)$, which is consistent with the suggested excitation of a bonding 1n electron from the ground state.