Volume 2, Issue 1

We demonstrate that SiO 2 nanoparticles coated with a gold island film (GIF) provide an efficient plasmonic platform for enhancing fluorescence intensity of chlorophyll-containing photosynthetic complexes. Fluorescence images obtained for single SiO 2 -Au coreshell nanoparticles mixed with photosynthetic complexes reveal very uniform emission patterns of a circular shape, similarly as observed for bare SiO 2 nanoparticles. The fluorescence enhancement of chlorophyll emission for SiO 2 -Au nanostructures is up to four-fold compared to bare SiO 2 nanoparticles and shortening of fluorescence decay indicates its plasmonic origin. For doublets or triplets of core-shell SiO 2 -Au nanoparticles, the intensity of emission is further increased as a result of hot-spot formation at the interfaces of such assemblies.

The proposed concept of Raman probe for nearfield optical microscopy raises the question about the similarity of fields acting on specimens deposited at the tip apex and contacting surface. The signal generated at these two close but different points is defined by local fields, so it is the ratio of the fields at these points, that is the quantity of interest here. This work is concerned with the application of a simple dipole model for the analysis of the ratio of fields at the tip apex and at contacting surface as a function of their separation.

High aspect ratio metal nanostructures have been the subject of a number of studies in the past, due to their pronounced resonances in the infrared that can be exploited to enhance vibrational spectroscopies. In this work, we investigate the nonlinear optical response of both individual and closely-packed assemblies of vertical hollow Ag nanopillars upon excitation with ultrafast laser pulses. In particular, the analysis of their nonlinear emission spectra evidences an intense two photon photoluminescence (TPPL) emission and a neat signature of second harmonic generation (SHG). Given the relatively low background, this pronounced nonlinear emission could be employed as a local probe for analytes trapped at the surface of the nanopillar or flowing through it. For this reason, these nanostructures may become appealing building blocks in multi-purpose devices for nonlinear photonics and sensing.