On the Influence of Pulse Shapes on Ionization Probability
  We investigate analytical expressions for the upper and lower bounds for the ionization probability through ultra-intense shortly pulsed laser radiation. We take several different pulse shapes into account, including in particular those with a smooth adiabatic turn-on and turn-off. For all situations for which our bounds are applicable we do not find any evidence for bound-state stabilization. 
C. Figueira de Morisson Faria, A. Fring and R. Schrader