The double resonance ionisation nozzle cooled spectroscopy (DRINCS) technique has been used to extend the existing vibrational constants for the lowest three ion-pair states of I2 with 0g+ symmetry using the B state as the first resonant intermediate. The E(P-3(2)), f(P-3(0)) and f(1D2) states now cover the range upsilon' = 0-422, upsilon' = 0-228 and upsilon' = 0-166 respectively. Potential energy curves beyond the previously existing RKR potentials have been generated using only the vibrational Dunham coefficients and the known asymptotic behaviour of the Coulombic branch of the potentials. These potentials have been used to simulate the DRINCS spectra and correctly reproduce the observed intensity minima in the envelope of the vibrational progression below 56000 cm-1. Above this the band intensities are very irregular because of homogeneous interactions with Rydberg states. The lifetimes of the f'(upsilon' = 0) state has been determined as 142 +/- 6 ns. The reason for this unusually long lifetime is discussed in terms of the electronic structure of the I+ (1D2) cation and the B (3PI(u) 0u+)state. The electronic transition dipole moment function, mu(f)' --> B(R), over the range 3.51-4.23 angstrom has also been determined by simulation of the dispersed fluorescence from the upsilon' = 11 level of the f'(0g+) ion-pair state and shows a maximum at 4.05 angstrom.
|Number of pages||15|
|Publication status||Published - 1 May 1994|
- OPTICAL DOUBLE-RESONANCE
- DIPOLE-MOMENT FUNCTION