Radio-Frequency Spectroscopy and Perturbation Analysis in CS A 1Π(υ = 0)

Abstract

Electric dipole rf resonances are observed in levels $\text{J\hspace{0.17em}=\hspace{0.17em}1}$ through 9 of $A^1\text{Π(υ\hspace{0.17em}=\hspace{0.17em}0)}$ of CS. A CS molecular discharge lamp is the source of the pumping ultraviolet radiation. Lambda doubling intervals ranging from 13 to 1787 MHz (100 kHz accuracy) and effective dipole moments of 0.6699 to 0.6786 D (0.0005 D relative error) for $\text{3\hspace{0.17em}≤\hspace{0.17em}J\hspace{0.17em}≤\hspace{0.17em}9}$ are obtained. These data are combined with measurements from the optical spectrum to extend the analysis of perturbations affecting $A^1\text{Π(0)}$ . Parameters for the off‐diagonal spin–orbit interaction between this and several triplet states, perturbation corrections to the empirical term value $T_0$ and rotational constant $B_0$ , and intermixing coefficients for the Stark effect are obtained. The observed variation of the Stark effect with rotational level is analyzed to give two dipole moments: $A^1{\text{Π(υ\hspace{0.17em}=\hspace{0.17em}0), μ\hspace{0.17em}=\hspace{0.17em}0.63(4) D; a′}}^3{\Sigma }^{+}\text{(υ\hspace{0.17em}=\hspace{0.17em}10), μ\hspace{0.17em}=\hspace{0.17em}1.7(4)}\mathrm{D}$ . Error limits include probable effects from neglected minor components. The factors contributing to state selectively in optical pumping of excited electronic states by the molecular discharge lamp or by white light are discussed.