Molecular Level Anticrossing in the CN Radical

A molecular level anticrossing experiment has been performed on the CN radical. The ${\mathrm{A}}^2{\mathrm{\hspace{0.17em}\; \Pi }}_{\text{3/2}}$ state is preferentially populated by chemical reaction and various sublevels of this state are crossed with sublevels of the B ²Σ⁺ state by tuning with a magnetic field. The levels are mixed and anticrossed by application of a perpendicular electric field and the anticrossing resonance is observed by monitoring the emission in the violet bands. A density matrix theory of level crossing and anticrossing has been developed which allows an arbitrary number of molecular states to be included in the computer calculation of the lineshape. This calculation has been carried out for the case of CN in the two and three level limit, and the predicted electric field dependence of the linewidth and intensity agrees with the experimental results.