  We analyze electronically excited nuclear wave functions and their coherence
when subjecting a molecule to the action of natural, pulsed incoherent
solar-like light, and to that of ultrashort coherent light assumed to have the
same center frequencies and spectral bandwidths. Specifically, we compute the
spatio-temporal dependence of the excited wave packets and their electronic
coherence for these two types of light sources, on different electronic
potential energy surfaces. The resultant excited state wave functions are shown
to be qualitatively different, reflecting the light source from which they
originated. In addition, electronic coherence is found to decay significantly
faster for incoherent light than for coherent ultrafast excitation, for both
continuum and bound wave packets. These results confirm that the dynamics
observed in studies using ultrashort coherent pulses are not relevant to
naturally occurring solar-induced processes such as photosynthesis and vision.
