Resonance Raman studies of I 3 – photodissociation in solution

Abstract

The triiodide ion in solution has two strong, featureless electronic transitions spanning the blue to mid-uv spectral region which dissociate to I 2 – - and atomic iodine. Recent femtosecond pump-probe experiments have shown that the diiodide ion product is formed vibrating coherently. [1] Numerical simulations of the photodissociation event, both in the isolated molecule[2] and with solvent explicitly present, [3] are in qualitative agreement with the data, but rely on an empirical LEPS potential surface parameterized to reproduce the structureless absorption bands only. In order to explore the photodissociative potential surface more precisely, we have measured resonance Raman spectra, including absolute scattering cross sections, for I 3 – in ethanol, ethyl acetate, and acetonitrile at excitation wavelengths from 266 to 416 nm, as well as in the preresonant region at 488 nm.