We apply optimal control theory to drive the sodium dimer molecule into a predefined target state. The latter consists of a linear combination of highly excited vibrational states in the electronic ground state. The obtained optimal field consists of separated pump- and dump-components. To determine the quality of the target-state control experimentally, it is possible to measure photoclectron spectra resulting from the interaction with a time-delayed probe pulse. The difference of spectra obtained in the case of pump-dump-probe and pump probe ionization directly reveals the probability density of the target wave-packet. (C) 2002 Elsevier Science B.V. All rights reserved.