FT-IR and Raman spectroscopic study of hydrated borates

FT-IR spectroscopy of supersaturated aqueous solutions of magnesium borate.

Polyborates in aqueous borate solution: a Raman and DFT theory investigation.

The fast and reversible switching of plasmonic color holds great promise for many applications, while its realization has been mainly limited to solution phases, achieving solid-state plasmonic color-switching has remained a significant challenge owing to the lack of strategies in dynamically controlling the nanoparticle separation and their plasmonic coupling. Herein, we report a novel strategy to fabricate plasmonic color-switchable silver nanoparticle (AgNP) films. Using poly(acrylic acid) (PAA) as the capping ligand and sodium borate as the salt, the borate hydrolyzes rapidly in response to moisture and produces OH- ions, which subsequently deprotonate the PAA on AgNPs, change the surface charge, and enable reversible tuning of the plasmonic coupling among adjacent AgNPs to exhibit plasmonic color-switching. Such plasmonic films can be printed as high-resolution invisible patterns, which can be readily revealed with high contrast by exposure to trace amounts of water vapor.

Dynamic Color-Switching of Plasmonic Nanoparticle Films.

Near edge x-ray absorption fine structure (NEXAFS) spectra at the boron K-edge were measured for aqueous boric acid, borate, and polyborate ions, using liquid microjet technology, and compared with simulated spectra calculated from first principles density functional theory in the excited electron and core hole (XCH) approximation. Thermal motion in both hydrated and isolated molecules was incorporated into the calculations by sampling trajectories from quantum mechanics/molecular mechanics simulations at the experimental temperature. The boron oxide molecules exhibit little spectral change upon hydration, relative to mineral samples. Simulations reveal that water is arranged nearly isotropically around boric acid and sodium borate, but the calculations also indicate that the boron K-edge NEXAFS spectra are insensitive to hydrogen bonding, molecular environment, or salt interactions.

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pH-dependent x-ray absorption spectra of aqueous boron oxides

Raman spectra of polyborate ions in aqueous solution

Boric acid solution (O.1mol/l) was passed through a column packed with strong base anion exchange resin, Diaion SA 20 A in the fluoride form (O.8 cm2 45 cm or O.8 cm2 95 cm bed), and the band formed on the column was eluted with pure water.The boric acid coRcentration in each fraction of the eMuent was determined by the acidbase titration with manitol. The atomic fraction of boron-10 in each fraction was determined by means of a Varian Mat CH 5 mass spectrometer, using the surface ionization method.In these experiments, it was found that:(1) Boron-10 was considerably enriched in the rear part of the band (e. g. aerr=1.06) and depleted in the frontal part (e. g. af=O.95).(2) The boric acid charged on the colum was nearly completely eluted with pure water.(3) Fluoride ion was scarcely detected in the eMuent (below 10-3 mol/1).(4) The elution curve became sharper with the decrease of flow rate.(5) The enriched amount of boron-10 increased with the decrease of flow rate, and with the elevation of column length and loading of boric acid.

Toshiyuki Hirao

Papers

Raman spectra of polyborate ions in aqueous solution

Separation of boron isotopes by means of strong base exchange resin in fluoride form