The REMPI spectroscopy of Cl2; a bound-free-bound route to the

The 1g(1D2) ion-pair state of Cl2 has been accessed via a two-photon, two-colour bound-free-bound route. An extensive vibrational progression is observed, overlapping high levels of the FOR EOg+(3P2) state. The absolute numbering is established from isotopic shifts and continuity with the known term values of ν′ = 0-6. The intermediate resonant state accessing the 1g(1D2) state is the unbound C1Φ1μ. The final state classification as Ω = 1 is confirmed by simulating the rotational band structure observed under perpendicular pump/probe polarization conditions using Hönl-London factors from a coherent superposition of intermediate JiMi states, not those appropriate to well-defined Ji and Mi states. These Hönl-London factors also reproduce the rotational linestrengths of the β1g(3P2); ν′ = 65 ← ← X; X; ν″ = 0transition observed under || and ⊥ polarization conditions when the pump photon energy lies in the continuum of the C1 ← X and B ← X absorption.