Enhanced nonlinear optical absorption of Au/SiO_2 nano-composite thin films

Nano metal-particle dispersed glasses are the attractive candidates for nonlinear optical material applications. Au/SiO2 nano-composite thin films with 3 vol% to 65 vol% Au are prepared by inductively coupled plasma sputtering. Au particles as perfect spheres with diameters between 10 nm and 30 nm are uniformly dispersed in the SiO2 matrix. Optical absorption peaks due to the surface plasmon resonance of Au particles are observed. The absorption property is enhanced with the increase of Au content, showing a maximum value in the films with 37 vol% Au. The absorption curves of the Au/SiO2 thin films with 3 vol% to 37 vol% Au accord well with the theoretical optical absorption spectra obtained from Mie resonance theory. Increasing Au content over 37 vol% results in the partial connection of Au particles, whereby the intensity of the absorption peak is weakened and ultimately replaced by the optical absorption of the bulk. The band gap decreases with Au content increasing from 3 vol% to 37 vol % but increases as Au content further increases.

The influence of nickel dopant on the microstructure and optical properties of SnO2 nano-powders

The microstructure and optical properties of Ni-doped SnO2 nano-powders are studied in detail. By Ni-doping, not only the grain size reduces, but also the grain shape changes from nano-rods to spherical particles. The crystallization becomes better with annealing temperature increasing. The band gap energy decreases as nickel doping level increases. The sp-d hybridization and alloying effect due to amorphous SnO2-x phase should be responsible for the band gap narrowing effect. Nickel dopant does not change the photoluminescence （PL） peak positions.

TDDFT study of excitation of water molecules with short laser pulses

We explore the excitation of water molecules subject to short and intense laser pulses in the frame of time-dependent density function theory （TDDFT） at the level of the time-dependent local-density approximation （TDLDA）, applied to valence electrons, coupled non-adiabatically to molecular dynamics （MD） of ions. We first study the optical absorption spectra of the water molecule as an observable in the ＂linear＂ domain and results are in good agreement with experiments. We then explore the influence of the laser frequency on the excitation. It is found that when the laser frequency is off-resonant or highly above the resonant region, the excitations are weak whereas for the resonant frequency case, the ionization is enhanced and bond lengths are enlarged. Furthermore, a direct coupling of ions with the laser pulse with the off-resonant frequency is found when investigating the OH bond lengths. We finally study the effect of laser intensity on the excitation of H 2 O and it is found that ionization increases when the laser intensity varies from low to high and we observe stable vibrations to Coulomb fragmentation when the ionization is up to typically two more charge units.

Highly efficient photocatalytic reduction of nitrogen into ammonia by single Ru atom catalyst supported by BeO monolayer

Ammonia(NH_(3))is one of the most important building blocks of the chemical industry and a promising sustainable energy carrier.Conventional production of NH_(3)via the Haber-Bosch process requires high temperature and high pressure,which is energy demanding and suffers safety issues.Photocatalytic nitrogen reduction reaction(NRR)is a green and sustainable route for NH_(3) production,and has been expected to be an alternative for NH_(3)production under mild conditions.However,solar-driven N_(2)activated has appeared as the bottleneck for photocatalytic NRR.In this work,we propose that single Ru atom supported by BeO monolayer is a promising photocatalytic single atom catalyst(SAC)for efficient N_(2)activation with visible illumination.The high efficiency originates from the enhanced absorption in the visible range,as well as the back-donation mechanism when N_(2)were adsorbed on the SAC.Our results show that N_(2)can be efficiently activated by the Ru/BeO SAC and be reduced to NH_(3) with extremely low limiting potential of-0.41 V.The NRR process also exhibits dominate selectivity respect to hydrogen evolution.

Microwave synthesis and spectroscopic characterization of manganese oxalate nanocrystals

The microwave synthesis of MnC204.2H2O nanoparticles was performed through the thermal double decomposition of oxalic acid dihydrate （C2H204.2H20） and Mn（OAc）2.4H2O solutions using a CATA-2R microwave reactor. Structural characterization was performed using X-ray diffraction （XRD）, particle size and shape were analyzed using transmission electron microscopy （TEM）. The chemical in the structures was investigated using electron paramagnetic resonance （EPR） as well as optical absorption spectra and near-infrared （NIR） spectroscopies. The nanocrystals produced with this method were pure and had a distorted rhombic octahedral structure.Manganese oxalate