We investigate the correlated electronic and nuclear motion in a model system as proposed by Shin and Metiu [J. Chem. Phys. 102, 9285 (1995)]. The quantum dynamics is studied during laser induced electronic transitions. Here, the influence of nonadiabatic coupling on the absorption spectrum is investigated and the Franck-Condon principle is illustrated in terms of the temporal changes of electronic and nuclear densities. In the case of intense field excitation, multiphoton processes become important, and electronic as well as vibrational wave packets are prepared. (C) 2004 American Institute of Physics.