Femtosecond wave packet propagation in spin-orbit coupled electronic states of the Na-2 molecule

The vibrational dynamics of the excited electronic A(1) Sigma(u)(+) state of Na-2 for two pump wavelengths lambda(pump) = 620 and 642 nm are investigated. Preparing a wave packet on the A state shows fast dominant oscillations with periods of similar to 312 and similar to 297 fs. For lambda(pump) = 620 nm a first revival centered around 47 ps is found and for lambda(pump) = 642 nm the first revival already appears after 14 ps (center). Fourier analysis of the 60 ps scans with a resolution of 0.05 cm(-1) enables the detailed identification of the excited vibrational levels of the A state. By comparison with RKR data, energy shifts of the level nu = 8 due to spin-orbit coupling (SOC) with the b(3) Pi(u) state is determined to be 0.85 cm(-1).