A-band resonance Raman spectra of 1,2-diiodoethane in cyclohexane solution.: Substituent effects on the 1-halo-2-iodoethane short-time photodissociation dynamics

Resonance Raman spectra of 1,2-diiodoethane in cyclohexane solution have been obtained in the A-band absorption. A resonance Raman intensity analysis was done to examine the short-time photodissociation dynamics of 1,2-diiodoethane. Significant bond length and bond angle changes were found for both C–I bonds and the C–C bond as well as the CCI and HCH bond angles. Comparison of the Franck–Condon region dynamics of 1,2-diiodoethane with diiodomethane suggests that the degree of coupling of the two C–I chromophores depends on both the relative geometry of the C–I bonds and their relative separation.