Manipulable and Hybridized,Ultralow‐Threshold Lasing in a Plasmonic Laser Using Elliptical InGaN/GaN Nanorods

Manipulating stimulated‐emission light in nanophotonic devices on scales smaller than their emission wavelengths to meet the requirements for optoelectronic integrations is a challenging but important step. Surface plasmon polaritons (SPPs) are one of the most promising candidates for sub‐wavelength optical confinement. In this study, based on the principle of surface plasmon amplification by the stimulated emission of radiation (SPASER), III‐Nitride‐based plasmonic nanolaser with hybrid metal–oxide–semiconductor (MOS) structures is designed. Using geometrically elliptical nanostructures fabricated by nanoimprint lithography, elliptical nanolasers able to demonstrate single‐mode and multimode lasing with an optical pumping power density as low as 0.3 kW cm^?2 at room temperature and a quality Q factor of up to 123 at a wavelength of ≈490 nm are achieved. The ultralow lasing threshold is attributed to the SPP‐coupling‐induced strong electric‐field‐confinement in the elliptical MOS structures. In accordance with the theoretical and experimental results, the size and shape of the nanorod are the keys for manipulating hybridization of the plasmonic and photonic lasing modes in the SPASER. This finding provides innovative insight that will contribute to realizing a new generation of optoelectronic and information devices.     

基于人工神经网络的脉冲激光烧蚀Ag纳米粒子胶体的预测和验证

为有效缩短蒸馏水中脉冲激光烧蚀制备Ag纳米粒子胶体工艺中繁琐的实验过程,采用LinNet PF神经网络平台对制备工艺与平均粒径及粒径分布的关系进行建模,并将其运用到平均粒径及其分布的预测中去,讨论了激光能量密度、激光重复率、烧蚀时间和平均粒径及其分布的关系.克服了以往单因素实验法不能正确反映制备工艺和平均粒径及其分布之间复杂的非线性关系的弱点.预测和验证结果均表明实验值和网络预测值之间相对误差都在10%以内,从而表明神经网络能够更精确、更可靠地逼近它们之间的非线性关系.该方法为有效、快捷、经济地开发研制金属纳米粒子胶体提供了新的思路和有效手段.     

二氧化钛纳米棒在可见光下的光催化活性及其在降解有机污染物中的应用

The FTO/TiO2 seed layer/TiO2 nanorods were prepared by ion beam deposition and hydrothermal methods. Under UV light, the photocurrent density of FTO/TiO2 seed layer/TiO2 nanorods can reach 1.39 mA/cm2, which is higher than that without seed layer and nanorods structure. Not only that, the FTO/TiO2 seed layer/TiO2 nanorods can also adsorb visible light, which overcomes the defect that traditional TiO2 can not absorb visible light. The photocurrent density of FTO/TiO2 seed layer/TiO2 nanorods can reach 0.21 mA/cm2 under visible light. The increased performance resulted from the deposition of the TiO2 seed layer, which can reduce the band gap of TiO2. FTO/TiO2 seed layer/TiO2 nanorods also exhibited high photodegradation ability for organic pollutant methylene blue (MB). Within 120 min, 77.3% MB can be degraded, and the degradation rates remained almost unchanged after four cycles. Not only that, compared with powdered photocatalysts, FTO/TiO2 seed layer/TiO2 nanorods is easy to recover, and it can be reused by rinsing it with water several times and drying it naturally after the reaction.     

Penta‐Twinned Copper Nanorods: Facile Synthesis via Seed‐Mediated Growth and Their Tunable Plasmonic Properties

The use of seed‐mediated growth as a versatile approach to the synthesis of penta‐twinned Cu nanorods with uniform diameters and controllable aspect ratios is reported. The success of this approach relies on our recent synthesis of uniform Pd decahedra, with sizes in the range of 6–20 nm. The Pd decahedral seeds can direct the heterogeneous nucleation and growth of Cu along the fivefold axis to produce nanorods with uniform diameters defined by the lateral dimension of the original seeds. Due to a large mismatch in the lattice constants between Cu and Pd (7.1%), the deposited Cu is forced to grow along one side of the Pd decahedral seed, generating a nanorod with an asymmetric distribution of Cu, with the Pd seed situated at one of the two ends. According to extinction spectra, the as‐obtained Cu nanorods can be stored in water under the ambient conditions for at least six months without noticeable degradation. This excellent stability allows us to systematically investigate the size‐dependent surface plasmon resonance properties of the penta‐twinned Cu nanorods. With the nanorod transverse modes positioned at 560 nm, the longitudinal modes can be readily tuned from the visible to the near‐infrared region by controlling the aspect ratio.     

溶胶凝胶法制备含银Na2O-B2O3-SiO2玻璃

提出以溶胶凝胶法制备含银Na₂O-B₂O₃-SiO₂玻璃的工艺及制备过程,用X射线衍射及红外吸收光谱分析制备过程中结构变化,用光学吸收谱、透射电镜及能谱分析确定银胶体粒子的存在及其分布.结果表明,溶胶凝胶法制备与传统熔融法制备的玻璃有相同的结构,且通过适当的热处理工艺可以获得尺寸有一定分布的银粒子.该方法既可以用于颜色玻璃的制备,其产品也可作为制备其他材料的原料.     

Influence of Au Photodeposition and Doping in CdS Nanorods: Optical and Photocatalytic Study

Au-modified CdS nanorods (100–200 nm × 5–10 nm) are synthesized via two different techniques, namely photodeposition and doping. The prepared samples are characterized by x-ray powder diffraction, transmission electron microscopy (TEM), and UV–vis and fluorescence spectroscopy. X-ray diffraction study confirmed the hexagonal phase of bare and Au-CdS samples, whereas, 5 wt% Au³⁺ doping into CdS resulted in a slight distortion in the crystal structure toward higher degree side. TEM images revealed the fine distribution of Au nanodeposits of size in the range of 2.5–4.5 nm on to the CdS surface in the photodeposited sample. The optical spectrum shows a significant red-shift in absorption onset (485 nm → 515 nm) and band-edge emission (505 nm → 512 nm) of CdS nanorods with the replacement of certain Cd²⁺ ions with Au³⁺. The influence of Au photodeposition and doping in CdS nanorods was comparatively tested by photooxidation of RhB (50 ppm) dye aqueous solution under direct sunlight irradiation (35–40 mWcm^?2). Our results point out that 5 wt% Au³⁺ doping into CdS nanorods remarkably improved its activity and stability due to homogeneous dispersion of charge throughout the crystal, quick Fermi level equilibration, and an improvement in ionic bond formation.     

TiO2纳米棒光阳极的制备及性能改进

首先采用水热法制备 TiO2纳米棒光阳极,并引入 Au@SiO2纳米颗粒对其性能进行改善。结果表明,Au@SiO2纳米颗粒的引入虽然增强了光吸收,但同时减少了染料在 TiO2纳米棒上的吸附量,反而导致了电池器件性能的下降。因此,在 TiO2纳米棒/Au@SiO2纳米颗粒结构上进一步生长一层 TiO2钝化层：一方面可增加染料吸附量;另一方面有利于减少电荷复合。基于这种光阳极组装的染料敏化太阳能电池获得了 2.34%的光电转换效率,较单一 TiO2纳米棒光阳极组装的电池效率提高了 60%。     

Determination of trace amount of silver in water samples by flame atomic absorption after preconcentration by ZnO nano sorbent

A simple and fast method based on solid phase extraction (SPE) applying zinc oxide (ZnO) nanoparticles and atomic absorption spectrometry (AAS) was developed for the trace amount determination of silver (Ag) in aqueous samples. The method linearity was in the range of 14 to 700 ng mL^?1. The extraction efficiency of Ag was greater than 98% and limit of detection (LOD) was 4.2 ng mL^?1. The preconcentration factor was 200 and the relative standard deviation (RSD%) of the method was 3.7% (n = 6).     

银反点阵列/TiO_2材料的制备及光催化性能研究

采用胶体晶体模板技术和磁控溅射工艺,制备了银反点阵列修饰TiO_2薄膜。用扫描电子显微镜、X射线衍射、紫外-可见分光光度计和四探针测试仪等手段对复合薄膜的结构和光催化性能进行了表征。结果表明,银反点阵列具有优良的导电性能,可有效抑制光生载流子的复合,增强载流子输运的效率,使TiO_2的光催化性大幅提升。