Saturation Effects in the Spatial and Energy Distributions in Short Pulse High Intensity Multiphonon Ionization.

We have calculated the spatial and electron energy structure for short pulse, high intensity multiphonon ionization taking into account saturation. Using an avoided crossing picture, we modeled multiphonon resonances induced by the high intensity AC stark effect. We have explicitly considered ionization due to the rising and falling edges of the laser pulse including saturation and ground state depletion. Using only the laser pulse duration as the adjustable parameter, our results show the dramatic modifications to both the spatial structure and photoelectron energy spectrum as saturation becomes important.