  In this work we present a hypothesis that spectral response of atoms or
molecules to a pulse of electromagnetic radiation with fast rising or falling
fronts would contain a unique emission line that is located approximately near
the frequency of the natural oscillations of optical electron. The emission of
this "pinging" spectral line would exist during the time that is determined by
the time of radiative energy loss by the optical electron. The amplitude of the
"pinging" spectral line would be higher for the pulses with faster raising or
falling fronts. The simulations using our previously developed model confirmed
existence of the "pinging" spectral response. If experimentally confirmed, this
work could lead to a new high sensitivity and high signal to noise ratio
stand-off detection techniques, a new type of LIDAR, and to other yet unknown
applications.
