Evidence of field evaporation assisted by nonlinear optical rectification induced by ultrafast laser

The controlled field evaporation of single atoms from a metal surface assisted by ultrafast laser pulses has recently been demonstrated. With nanosecond pulses, pertinent physical mechanisms of this phenomenon were proposed. However with ultrafast laser pulses, these conventional mechanisms cannot explain experimental results. A model is presented in which the THz pulse generated by optical rectification at the metal surface plays an important role in the ion emission. Experiments are carried out on tungsten and aluminium tips to check the presence of this nonlinear process. A good agreement between the predictions of our model and the experimental data is found.