We studied the time evolution of the wave packet formed by the excitation of the Ba...FCH3 complex with a 120 fs laser pulse at 745 nm to its electronic (A) over bar' state which is repulsive at the ground state geometry and decays to Ba and CH3F fragments. By applying probe pulses with different wavelengths of 400 and 267 nm, respectively, we observed strongly different time dependences of the pump-probe signals for the BaF+ and Ba+ ions determined by the Franck-Condon windows available in both cases. The experimental results are qualitatively confirmed by theoretical studies based on ab initio calculations of the corresponding potential energy surfaces. (C) 2002 Elsevier Science B.V. All rights reserved.