Preparation of a wave packet through a mixed level in Li2; predissociation of one member of the superposition

Through a mixed level, which has characters of both the A 1 Σ u + and b3Πu states of Li2, several singlet and triplet Rydberg states are accessed simultaneously using an ultrafast laser. The electronic, vibrational and rotational wave packets of these Rydberg states are detected. Since a single member of the excited superposition, 2 3 Σ g + (v = 12, N = 16), is predissociative, the intensities of the quantum beats that have a component of this state decrease much faster with time (≈250 ps) than the other stable states. The polarization dependence of the quantum beats is utilized to assign the spectra.