OPTICAL OPTICAL DOUBLE-RESONANCE SPECTROSCOPY OF CL2 - ANALYSIS OF THE ALPHA-3-PI(1U)-CHI-1-SIGMA-G+ SYSTEM

The A3Π(1u)-X1Σg+ absorption system of Cl2 is studied by optical-optical double resonance using the 1g(3P2)-A3Π(1u)-X1Σg+ photo-excitation sequence: We label a particular level of the intermediate A3Π(1u) state through the 1g(3P2)-A3Π(1u) transition and extract this system from the visible absorption spectrum which contains the much stronger B3Π(0u+)-X1Σg+ system in the same region. The vibrational bands of 35Cl2, with 2≦v′≦13 and 1≦J′≦51, are measured to within 0.02 cm-1 and rotationally analyzed by including the heterogeneous interactions with other bound states, A′3Π(2u), B′3Π(0u-), and B3Π(0u+). The intensity anomaly found in the transitions to the interacting A3Π(1u) and B3Π(0u+) states is interpreted as an interference effect between parallel (B-X) and perpendicular (A-X) transition amplitudes, whose ratio ( μ|e μ⊥e) is determined to be 4.8. © 1991.