Knowledge Bank

The dipole moment of the electronically excited $A2\Pi$ state of the CN radical has been measured as 0.56 $\pm$ 0.03 D by analyzing the electric field dependence of the level anti-crossing spectral linewidth. The theory of the Stark effect indicates that the broadening depends upon two parameters, the $A2\Pi$ dipole moment and the electric dipole transition moment between the $A2\Pi$ and $B2\Sigma +$ states. The spectral linewidth is rather insensitive to the value of the transition moment, and this quantity is not well determined from the experimental data.