  Using tomographic reconstruction we determine the complete internuclear
quantum state, represented by the Wigner function, of a dissociating I2
molecule based on femtosecond time resolved position and momentum distributions
of the atomic fragments. The experimental data are recorded by timed ionization
of the photofragments with an intense 20 fs laser pulse. Our reconstruction
method, which relies on Jaynes' maximum entropy principle, will also be
applicable to time resolved position or momentum data obtained with other
experimental techniques.
