  The dynamics of atomic levels resonantly coupled by a coherent and intense
short high-frequency laser pulse is discussed and it is advocated that this
dynamics is sensitively probed by measuring the spectra of the particles
emitted. It is demonstrated that the time-envelope of this laser pulse gives
rise to two waves emitted with a time delay with respect to each other at the
rising and falling sides of the pulse, which interfere in the time domain. By
computing numerically and analyzing explicitly analytically a show-case example
of sequential two-photon ionization of an atom by resonant laser pulses, we
argue that this dynamic interference should be a general phenomenon in the
spectroscopy of strong laser fields. The emitted particles do not have to be
photoelectrons. Our results allow also to interpret the already studied
resonant Auger effect of an atom by intense free electron laser pulses, and
also to envisage experiments in which photons are emitted.

Atomic and Molecular Clusters;Atomic Physics