Laser nonuniformity and ac Stark shift effect on two-photon resonant three-photon ionization process of cesium atom

Summary form only given. We investigated the effect of temporal and spatial characteristics not only on the ionization spectrum but on the excited-state population. From the calculational results in which Gaussian temporal and spatial variation was assumed, it was found that the nonuniformity of a laser made the shift of ionization peak frequency different from that of excitation peak frequency. This result indicates that measurement of an ac Stark shift cross section by detecting the fluorescence emitted from an excited state might give the different results comparing with the ionization spectrum measurement case.