Single crystal, silver particles of 215 +/- 10 nm size were synthesized in solution using the hydrogen reduction method and were characterized by UV-visible extinction spectroscopy and electron microscopy. The extinction spectra reveal the presence of higher order multipoles of the plasmon resonance, such as quadrupole, octupole, and hexadecapole, in addition to the dipole. The formation of higher order multipoles was continuously monitored during the particles growth. Mie extinction calculations were performed and are in good agreement with the measured extinction spectra. The frequency shift of all plasmon modes was measured as a function of the refractive index of the surrounding dielectric medium.

The effect of the particle size and interparticle distance on the coherent plasmon coupling was studied in 2D arrays of silver nanoparticles. The plasmon coupling leads to the formation of a cooperative plasmon mode characterized by an intense and narrow peak in the blue spectral range. The arrays were fabricated via the self-assembly of the nanoparticles on poly(4-vinylpyridine)-modified glass substrates. Changing the ionic strength of the aqueous nanoparticle suspension prior to the self-assembly provided a possibility for controlling the interparticle distance in the arrays. The study revealed an optimum particle size around 86 nm and the corresponding optimum interparticle distance of about 107 nm for the strongest plasmon coupling, as determined from the most intense and sharpest resonance that was observed in water. Changing the dielectric medium will conceivably result in different values for the optimal particle size and interparticle distance.

Polyoxoniobates are exceptional amongst polyoxometalates in that they can potentially perform base catalysis in water, a process in which a proton is bonded to an oxo ligand, and a hydroxyl is released. Catalytic decomposition of chemical warfare agents such as organofluorophosphates that were used recently in the infamous civilian attacks in Syria is one opportunity to employ this process. Upon evaluation of the polyoxoniobate Lindqvist ion, [Nb 6 O 19 ] 8-, fast neutralization kinetics was discovered for the breakdown of the nerve agent simulant diisopropyl fluorophosphate (DFP). The polyoxoniobates were also tested against the nerve agents Sarin [a]

Metal–organic frameworks are shown to degrade organophosphorus compounds in non-aqueous environments, highlighting appropriate simulants for the nerve agent sarin.

No abstract