Nonlinear plasmonics at planar metal surfaces

We investigate the nonlinear optical response of a noble metal surface. We derive the components of the third-order nonlinear susceptibility and determine an absolute value of χ((3))≈0.2 nm(2) V(-2), a value that is more than two orders of magnitude larger than the values found for typical nonlinear laser crystals. Using nonlinear four-wave mixing (4WM) with incident laser pulses of frequencies ω(1) and ω(2), we generate fields oscillating at the nonlinear frequency ω(4WM)=2ω(1)-ω(2). We identify and discuss three distinct regimes: (i) a regime where the 4WM field is propagating, (ii) a regime where it is evanescent, and (iii) a regime where the nonlinear response couples to surface plasmon polaritons.     

Combustion Based Synthesis of AlN Nanoparticles Using a Solid Nitrogen Promotion Reaction

Combustion based synthesis of AlN nanoparticles using the “solid nitrogen” promotion reaction was investigated in Al₂O₃ + 3Mg system in nitrogen atmosphere. A controlled amount of Mg + 0.5NH₄Cl mixture as a solid source of nitrogen was blended with the Al₂O₃ + 3Mg starting system and the synthesis reaction of AlN nanoparticles was conducted using the exothermic heat of the entire reaction system. The resulting AlN nanoparticles were characterized by X‐ray diffraction (XRD), Raman and Fourier transform infrared spectroscopy (FTIR), PL spectroscopy, field‐emission scanning electron microscopy, transmission electron microscopy, and Brunauer–Emmett–Teller surface area techniques. The analysis results confirmed that single phase and crystalline AlN nanoparticles with an average size of 50–500 nm were obtained from the developed approach. Photoluminescence spectra of AlN nanopowders under the excitation of 230–270 nm UV light revealed that AlN emits yellow‐red light having a wavelength near to 590 nm. The chemistry of the combustion process is discussed and the basic reactions that led to the formation of AlN are presented.