Measurements of the radiative lifetimes of the Cl2 ion-pair states by optical-optical double resonance

The technique of optical-optical double resonance spectroscopy is used to study the radiative lifetimes of the Cl 2 ion-pair states from the fluorescence decays. This experiment allows us to classify the six gerade states correlating to the lowest asymptote Cl − ( 1 S)+Cl + ( 3 P) into two groups from the fluorescence lifetimes. One involves the four spin-orbit components of the 3 Π g state, O + g ( 3 P 2 ), O − g ( 3 P 2 ), 1 g ( 3 P 2 ), and 2 g ( 3 P 2 ), showing short lifetimes of 4–5 ns. The other includes those of 3 Σ − g with lifetimes almost an order of magnitude longer; 44.6±0.5 ns for 0 + g ( 3 P 0 ) and 73.8±3.0 ns for 1 g ( 3 P 1 ).