Satellites of the Dipole-Forbidden Transitions to the Low-Lying 2S1/2 and 2D3/2,5/2 Excited States of K, Rb, and Cs Atoms in the Spectra of Gas-Phase Mixtures with CF4

Abstract

The luminescence excitation spectra of the D₁ resonance line of atoms K, Rb, and Cs in gas mixtures with CF₄ are found to contain satellite transitions, which correspond to the transition of an atom to the states (n – 1)d ²D_3/2,5/2 and (n + 1)s ²S_1/2, where n = 4, 5, and 6 for K, Rb, and Cs, respectively, with the simultaneous excitation of CF₄ molecule vibrations at the IR active mode frequency ν₃ with a quantum energy of 1283 cm^–1. These satellite transitions are A(ns ²S_1/2) + CF₄(ν₃ = 0) + hν → A((n – 1)d ²D_3/2,5/2) + CF₄(ν₃ = 1) and A(ns ²S_1/2) + CF₄(ν₃ = 0) + hν → A((n + 1)s ²S_1/2) + CF₄(ν₃ = 1), where A = K, Rb, and Cs. The appearance of an optical coupling between the upper and lower states of these asymptotically (at \({{R}_{{{\text{A}} - {\text{C}}{{{\text{F}}}_{4}}}}}\) → ∞) forbidden transitions is shown to be caused by the interaction of the dipole moment of the ν₃ = 1 ↔ ν₃ = 0 vibrational transition in the CF₄ molecule with the dipole moments of the electronic transitions np ²P_1/2,3/2 ↔ (n – 1)d ²D_3/2,5/2 and np ²P_1/2,3/2 ↔ (n + 1)s ²S_1/2 in an alkali metal atom; as a result of this interaction, the upper state of the satellite transition acquires admixtures of the A(np ²P_1/2,3/2)CF₄(ν₃ = 0) resonance states.