Femtosecond field ion emission by surface optical rectification

We show that a model based on the surface optical rectification effect associated with the nonlinear response of free electrons may explain quantitatively, without adjustable parameters, all the observed features of the ultrafast laser-assisted field-ion emission from metal tips. Moreover, the same model provides also a plausible explanation for the low-fluence ultrafast laser ablation recently observed in metal surfaces and nanoparticles. We further test our model with experiments of ultrafast laser-assisted field-ion emission from tungsten tips in the tomographic atom probe.