Enhanced optical absorption in semiconductor nano- particles enabled by nearfield dielectric scattering

The optical absorption of semiconducting AgBr nanocubes is significantly increased by up to 5 times in the measured spectral range when they are bonded to the surface of dielectric SiO2 nanospheres through electrostatic interaction. The absorption enhancement factor depends on the wavelength and the size of the SiO2 nanoparticles （NPs）. Finite-difference time-domain calculations provide the nearfield intensity mapping of a heterostructure that is composed of a AgBr nanocube in close contact with a SiO2 nanosphere. The electric-field distributions indicate the field enhancement near the SiO2/AgBr interface due to light scattering and absorption enhancement in the AgBr nanocube, implying that the enhanced scattering nearfield increases the absorption cross section of the AgBr nanocube. The absorption cross-section spectra calculated using Mie theory agree with the experimental observations. This discovery sheds light on the utilization of dielectric spherical particles to increase the absorption in semiconductor NPs, thus improving the light-harvesting efficiency for solar-energy conversion.

Structural elucidation, theoretical investigation using DFT calculations,thermal and dielectric analyses of new zinc(Ⅱ) based inorganic–organic hybrid

A novel interesting d^（10） metal hybrid, [1,2-C_6H_（10）（NH_3）_2]ZnCl_4; 1,2-diammoniumcyclohexane tetrachlorozincate（II） was grown, structurally characterized and their vibrational as well as thermal and dielectric proprieties were studied. A preliminary single crystal X-ray diffraction structural analysis has revealed that the latter crystallizes in the monoclinic system（space group C2/c）. Its unit cell dimensions are a = 32.394（9） ？, b = 12.217（4） ？, c = 10.175（3） ？, β = 97.852（13）° with Z = 12 and the refinement converged to R = 0.034 and ωR = 0.065. Hirshfeld surface analyses, especially d_（norm）surface and fingerprint plots were used for decoding intermolecular interactions in the crystal network. The optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of the present compound were theoretically examined by the DFT/B3 LYP method with the Lan L2 DZ basis set. The thermal and dielectric analyses suggested the presence of ferroelectric phase transition at 314 K.

Enabling Reaction Selectivity of Platinum Catalysts by Photoinduced Electronic Effects

Reaction selectivity is crucial to producing target molecules of importance with minimum waste.This work reports an efficient and green strategy to improve reaction selectivity in visible-light-mediated chemical transformations by employing Pt/SiOx photocatalysts,which is ascribed to light-induced surface electronic modification in the small Pt nanocrystals.This strategy has been successfully applied to synthesize commercially valuable but thermodynamically unfavorable arylhydroxylamines with high selectivity via partial hydrogenation of the respective nitroarenes.Surface modification of the small Pt nanocrystals with triethanolamine(TEA)molecules further optimizes the Pt electronic structure to favor the reaction selectivity.The light-induced surface electronic structure alterations and the TEA chemical modification act synergistically to prevent the readsorption of desorbed electron-rich arylhydroxylamines.This prevents the complete hydrogenation of arylhydroxylamines to respective anilines,leading to high arylhydroxylamine selectivity of 81−91%.In addition,photoillumination of Pt nanocrystals always accelerates the reaction kinetics significantly regardless of their surface modification.

Investigation on refractive index sensing of single silver nanoparticle at tightly focused light illumination

Based on the generalized Mie theory,refractive index sensing characteristics of single silver nanoparticle respectively illuminated by tightly focused linearly-polarized and radially-polarized light beams are investigated. The spectra for localized surface plasmon resonances(LSPR) under different dielectric environments demonstrate that distinct dipolar and quadrupolar resonances can be always observed for the case of radial polarization,while there is only strong dipolar resonance for the case of linear polarization. The dipolar mode has a higher sensitivity. However,the figure of merit(FOM) for the quadrupolar resonance is much higher than that for the dipolar resonance,because the quadrupolar resonance has a narrower width.