Evidence of Field Evaporation Assisted by Nonlinear Optical Rectification Induced by Ultra Fast Laser

We investigate the physical mechanism of the field ion emission in the case of ultra-fast laser pulses which is based on the nonlinear optical properties of surfaces: the optical rectification effect on metal surface. The optical rectification is based on nonlinear second order processes which occur in all non-centro-symmetric materials and at the surface of metals where the electronic density of states exhibits a discontinuity that yields strong anharmonic and nonlinear effects. Several experiments have been realised on tungsten and aluminium tips. A good agreement between the model and experimental data is found