OPTICAL-OPTICAL DOUBLE-RESONANCE STUDIES OF THE HALOGEN ION-PAIR STATES .3. THE F(0(U)+)-]X(0(G)+) TRANSITION DIPOLE-MOMENT FUNCTION IN I(2)

The F(0u+)(2) second cluster ion-pair state has been populated by the OODR scheme F(0u+)(2) valence transition F(v') --> X 1-SIGMA(g)+, for v' = 0, 4, 9, 19 has been dispersed. Using the upper and lower state potentials from previous RKR analyses, the transition dipole function mu(FX)(r) is obtained between 3.1 and 4.2 angstrom by fitting the envelope of the highly oscillatory structure and is placed on an absolute footing from the known lifetime of the v' = 0 level of the F state. The F --> X 1-SIGMA(g)+, and f(0g+)(2) --> B(0u+) transition dipoles show a very different behaviour over the range r = 3.1-3.6 angstrom. This is interpreted in terms of the rapidly changing electronic configurations of the ion-pair states near their equilibrium separations,