One-dimensional and two-dimensional arrays of nanoholes generated by laser in the semiconfined configuration

We have shown that nanoporosity can be generated on metal surfaces by nanosecond laser-matter interactions in the semiconfined configuration. The scanning electron microscope analysis has shown that nanoholes of similar to 25-50 nm in diameter, arranged in one-dimensional (1D) and two-dimensional (2D) irregular and regular arrays, have been formed. The interpretation is based on the generation of a dispersive, dissipative system of nonlinear solitary plasma waves (humps) that leave temperature/pressure fingerprints on the metal surface. It has been shown that the 1D irregular array of nanoholes can be interpreted as a result of the irregular string of solitary humps obtained by numerical simulation based on the Benney pd equation with the Gaussian perturbation. The 2D random array of nanoholes can be interpreted as a result of random solitary humps that can be obtained by numerical simulation from the Benney equation with the periodic perturbation. The regular string of nanoholes has been shown to appear as a result of breather modes (bound state of solitons), the numerical simulation of which has been based on the Boussinesq equation. The regular 2D array of nanoholes has been interpreted as fingerprints of breather modes, in agreement with the result of the numerical simulation of Tajiri and Murakami, [J. Math. Phys. 34, 2400 (1993)], based on the Kadomtsev-Petviashvili equation. (c) 2006 American Institute of Physics.