PERTURBATION ANALYSIS FOR THE $A^{2}\Pi$ AND $X^{2}\Sigma^{+}$ STATES OF CN

Abstract

Deperturbed vibration-rotation constants of the $A^{2}\Pi$ and $X^{2}\Sigma^{+}_{1}$ states of CN are obtained. Microwave and optical data from several sources are combined using a weighted, nonlinear least squares fitting routine. The diagonalized effective Hamiltonian matrix contains as many as two $^{2}\Pi$ and two $^{2}\Sigma^{+}$ mutually interacting vibronic levels. The deperturbed constants and interaction matrix elements obtained provide a significantly more accurate representation of all perturbed and unperturbed observed lines than the previously reported $values^{2}$ The electronic factors of the spin-orbit and rotation-electronic perturbation matrix elements for the $A\sim X$ and $A\sim B$ interactions are determined and several previously unreported perturbations are detected and analyzed. Merged constants and Dunham coefficients are calculated and a detailed statistical treatment of the parameters and error estimates is included.