Ultrafast photodissociation of I3− in solution: Direct observation of coherent product vibrations

We report the observation of terahertz oscillations in transient transmission measurements following femtosecond UV photolysis of I−3 in ethanol solutions. Transmission signals at 620 nm and at 880 nm, which are above and below the λmax of the known absorption of I−2 oscillate at precisely opposite phase. This and other results presented indicate that though the oscillations we are observing coherent vibration of the I−2 photofragment.