Abstract
The authors study the resonance lineshape in two-photon ionisation of atoms when the power broadening due to the bound-bound transitions is by far the dominant broadening mechanism. The authors consider the effect on the lineshape of turn-on of the laser-atom interaction, spontaneous emission and laser linewidth, and show that several different types of lineshapes can result depending on the conditions involved. The authors also consider the photoelectron spectrum, and show that it is also sensitive to these same parameters.