A vibrational progression that is hidden in a featureless spectrum of induced absorption and stimulated emission was found in time-resolved absorption change spectra. The ultrahigh time resolution of the pump probe measurement made by using an ultrashort laser pulse localizes the wave packet along the potential multimode hyper surfaces, represented by a vibrational progression. The transition energy of the induced absorption and stimulated emission corresponds to a localized point (space) on the hyper surface, which is visited by the wave packets with fixed phases.