Repulsive van der waals forces self-limit native oxide growth.

Silicon is one of the most studied materials, yet questions remain unanswered about its unusual property of growing a self-limiting native oxide that attains its final thickness in a matter of hours yet months later has not grown further. For the first time, we have explored this self-limiting growth in terms of repulsive van der Waals (vdW) forces generated by the combination of material properties inherent to the system. These repulsive forces represent an energy barrier preventing additional oxidizing chemicals, mainly oxygen and water, from adsorbing on the surface as well as hindering diffusion of those that do adsorb toward the interface.

Fiber-optic laser sensor for mine detection and verification.

What we believe to be a new optical approach for the identification of mines and explosives by analyzing the surface materials and not only bulk is developed. A conventional manually operated mine prodder is upgraded by laser-induced breakdown spectroscopy (LIBS). In situ and real-time information of materials that are in front of the prodder are obtained during the demining process in order to optimize the security aspects and the speed of demining.

Fiber-optic evanescent-field laser sensor for in-situ gas diagnostics.

A compact, rugged and portable fiber-optic evanescent-field laser sensor is developed for the detection of gaseous species in harsh environments such as volcano fumaroles or industrial combustion of glass furnaces. The sensor consists of an optical multi-mode fused silica fiber with jacket and cladding removed and the bare fiber core in direct contact with the surrounding molecules. The beam of a single-mode DFB diode laser with an emission wavelength centered at 1.