A novel technique for suppression of the multi-photon fluorescence contribution in second-order nonlinear optical hyper-Rayleigh scattering experiments is described. The technique takes advantages of the demodulation and the phase shift in the frequency domain of the time-delayed (multi-photon) fluorescence in the time domain. We demonstrate the effectiveness of demodulation at high modulation frequencies of the fundamental laser beam by determining the molecular second-order nonlinear polarizability for a reference molecule under fluorescent conditions. The value that was obtained for crystal-violet in methanol with 9,10-diphenylanthracene added as a centrosymmetric fluorophore compares very well with the values that were previously obtained. The possibility of complete suppression of all fluorescence, based on phase-sensitive measurements in quadrature with the fluorescence, is also discussed.

Spurred by research in magnetoplasmonics, plasmon-enhanced magneto-optical effects and active plasmonics, the demand for hybrid magnetic-plasmonic nanoparticle-based materials of optical quality is high. Currently used synthesis methods involve possibly interfering polymer media or polyelectrolyte interlayers, grooved supports or non-transparent substrates. To obtain homogeneous, partially transparent and polymer/polyelectrolyte-free magnetic-plasmonic nanocomposites with angle-independent optical properties, we produced hybrid gold-magnetite and silver-magnetite nanocomposites by a novel Layer-by-Layer synthesis using short bifunctional molecular linkers on glass substrates. Resulting nanocomposites had high nanoparticle filling fractions and showed tunability of the plasmon wavelength over a very broad spectral range by changing composite thickness through the number of added nanoparticle layers. The angle-independence of optical properties and the abilities to switch the plasmonic material and to tune the plasmon resonances of the magnetic-plasmonic composites make these materials a unique platform for magnetoplasmonic research.

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Noble metal nanoparticles (NPs) can efficiently release heat under optical excitation. Applying this principle of plasmonic heating, earlier work on incorporation of gold NPs into hydrophilic or hydrophobic membranes resulted in improved fluxes under laser irradiation without significantly lowering their selectivities. The present study aims at extending the concept of localized heating (plasmonic heating) of membranes to cheaper silver NPs and more energy efficient LED light instead of gold NPs and a laser device. In addition, the application range of the localized heating for membranes is now extended to pervaporation where the evaporation step is expected to benefit from the localized heating. Silver NPs were incorporated into the PDMS based pervaporation membranes by an in situ method, as confirmed by TEM images and UV-Vis spectra. The influence of the plasmonic heating on pervaporation performance of Ag-PDMS membranes was investigated by applying sweep gas pervaporation coupled to 400 nm LED light irradiation. The results indicate that applying LED light irradiation can significantly improve the pervaporation performance of Ag-PDMS membranes. It was concluded that plasmonic heating is an attractive strategy to enhance the pervaporation membrane performance.

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