Zeeman Effect for PerturbedN2+Terms

The Zeeman effects for the perturbed terms in the $v=1\mathrm{} \mathrm{and} 3$ levels of the upper ${}_{}{}^2{}_{}{}^{}\Sigma$ state of ${\mathrm{N}}_2^{+}$ have been investigated at various field strengths up to 27,000 gauss. At the points of maximum perturbation the Zeeman patterns are doublets for the moderate and high field strengths. At high field strengths the unperturbed lines, of the same $K$ value as the most perturbed lines, also become doublets under the influence of the magnetic field. This is attributed to a Paschen-Back effect. For $K$ values greater than those of the maximum perturbation point, all the lines exhibit an asymmetric broadening in the field. A consideration of the interactions with the perturbing ${}_{}{}^2{}_{}{}^{}\Pi$ state gives an explanation of the patterns observed.