The relative fluorescence intensities of all the strong electronic transitions from five of the first cluster of ion-pair (IP) states of I2 and from three states in the second cluster have been measured. The fluorescence, in most cases from v' = 0, was dispersed and comprised both discrete and continuous (bound --> free) spectra. These were fitted and each simulated electronic spectrum integrated separately to give relative values of the Einstein A-coefficients (summed over final vibrational states) for each transition. Using previously reported lifetimes, transition dipoles for each of the parallel transitions from nine IP states are deduced, together with some of the stronger perpendicular transition dipole moments. At R(e) of the ion-pair states, mu-perpendicular-to (five transitions observed) is almost constant at 0.2-0.3 D, but mu-parallel-to ranges between 0.7 and 3.7 D. There is a marked difference in the parallel transition moments associated with some g/u pairs in the same cluster of IP states which can be accounted for by the balance of p(sigma) and p(pi) occupancy in I+, combined with an interference effect in the electron transfer arising from the double vacancy in a p(sigma) or p(pi) orbital. The relative value of the transition dipoles for p(sigma) p(sigma) and p(pi) p(pi) electron transfer, M(sigma-sigma)/M(pi-pi), is estimated to be congruent-to 3.8:1 around R(e) of the IP states. The measured A-coefficients imply departures from the pure precession model of up to 20% in terms of the p(sigma)/p(pi) occupancy.
|Number of pages||18|
|Publication status||Published - Mar 1992|
- OPTICAL DOUBLE-RESONANCE