Mass-resolved multiphoton ionization spectroscopy of jet-cooled Cl2. I. Bound-free-bound spectroscopy
Spectroscopic constants, obtained using two-color optical double resonance via repulsive intermediate states, are presented for four ion-pair states of Cl2; i.e., the E(0+g), β(1g), f(0+g), and G(1g) states. One-color excitation, also via a repulsive intermediate state, has been used to further extend the vibrational data for the β(1g) state. The same pumping scheme has been used to extend a vibrational progression in the [2Π1/2]c4s; 1g Rydberg state. The absence of perturbations when the [2Π1/2]c4s; 1g Rydberg and the β(1g) ion-pair states cross, together with the key role played by the intermediate C(1u) state in accessing both singlet and triplet final states, are discussed in terms of the changes in spin-orbital coupling schemes that are required on bond stretching.