Knowledge Bank

The Goodman $bands1$ form the strongest evidence for the existence of bound states in the region of $I2$.We have recorded the Goodman system in fluorescence following one and two-color excitation. Spectra have been obtained for both $127I2$ and $129I2$ using dye laser frequencies covering $16500-18500cm-1$. At high resolution each band is resolved to reveal a cluster of 4-15 rotational lines. Our analysis has shown that the upper state is accessed via a resonance enhanced three-photon absorption process. A vibrational and rotational analysis has positively identified the upper terminus as the $FO\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}u$ state ($Te=47218cm-1$), a member of the second tier of ion-pair states.