Signatures of multiphoton and tunneling ionization in the electron-momentum distributions of atoms by intense few-cycle laser pulses

We present angle-resolved electron momentum distributions for above-threshold ionization (ATI) of argon in an intense, linearly polarized laser pulse. Our results were obtained by solving the time-dependent Schrodinger equation and by using a model based on the strong field approximation (SFA). Many features of the spectra such as ATI peaks, their substructure in the energy domain and their dominant angular momentum can be understood within the familiar SFA model.