  The observable line shape of the spontaneous emission depends on the
procedure of atom's excitation. The spectrum of radiation emitted by a
two-level atom excited from the ground state by a pi pulse of the resonant pump
field is calculated for the case when the Rabi frequency is much larger than
the relaxation rate. It is shown that the central part of the spectral
distribution has a standard Lorentzian form, whereas for detunings from the
resonance that are larger than the Rabi frequency the spectral density falls
off faster. The shape of the wings of the spectral line is sensitive to the
form of the pi pulse. The implications for the quantum Zeno effect theory and
for the estimates of the duration of quantum jumps are discussed.
