Modeling of femtosecond laser induced photoemission

The study of femtosecond laser induced electron emission has become important in recent years because of its application in imaging and as a femtosecond electron source. Most of the experimental studies in this area have been between the multiphoton and optical tunneling regimes where the Keldysh parameter is close to 1. Many different models have been used to describe the emission mechanism in this region including optical field emission, over-barrier emission and multiphoton emission. Here, we present a comparison of a model that combines optical field emission and multiphoton emission with pure multiphoton emission and tunneling models. A comparison of the models with experimental data including the peak-to-base ratio, energy spectrum etc. is also presented.