Photodissociation dynamics of iodoform in solution

The photodissociation dynamics of iodoform (CHI3) in acetonitrile and cyclohexane were investigated by femtosecond pump-probe spectroscopy and nanosecond laser flash photolysis. We have measured transient absorption spectra in the spectral region of 370-730 nm and kinetics at selected wavelengths on a femtosecond-microsecond time scale. We assign the observed photoproduct with absorption maxima at 450 and 600 urn, formed upon excitation of iodoform at 350 nm in acetonitrile and cyclohexane, to the isomer of iodoform, iso-iodoform (CHI2-I). The iso-iodoform is most probably formed via an in-cage recombination of the produced photofragments, the I atom and the CHI2 radical, with an similar to7 ps time constant. The lifetime of the iso-iodoform is found to be similar to1.8 and 0.2 mus in cyclohexane and acetonitrile, respectively.