Ionization with chirped pulses is studied using the Na-2 molecule as a numerical example. Bondlength expectation-values are determined for different linear chirp parameters. It is shown that under certain conditions the photoelectron spectra can exhibit a pronounced interference structure which has an analogy ill oscillatory patterns and the rainbow structure found in the scattering amplitude for atom-atom collisions. (C) 2003 Elsevier Science B.V. All rights reserved.