退火对Pb辐照Al2O3单晶发光特性的影响

研究了230MeV的²⁰⁸Pb²⁷⁺辐照Al₂O₃样品及随后在600,900,1100K高温条件下退火后的光致发光特性。从辐照样品的测试结果可以清楚地看到在波长为390,450nm处出现了强的发光峰。辐照量为1×10¹³ions/cm²时,样品的发光峰最强。经过600K退火2h后测试结果显示,380nm发光峰剧烈增强,而其他发光峰显示不明显。在900K退火条件下,380nm的发光峰开始减弱,而在360,510nm出现了明显的发光峰,至到1100K退火完毕后380nm的发光峰完全消失,而360,510nm的发光峰相对增强。从被辐照样品的FTIR谱中看到,波数在460~510cm^-1间的吸收是振动模式,经过离子辐照后,吸收带展宽,随着辐照量的增大,Al₂O₃振动吸收峰消失,说明Al₂O₃振动模式被完全破坏。1000~1300cm^-1之间为Al—O—Al桥氧的伸缩振动模式,辐照后吸收带向高波数方向移动,说明其振动模式受到影响。辐照剂量较小的样品,损伤程度相对较低,经退火晶化后,振动模式基本恢复到单晶状态;辐照剂量较高的样品,损伤程度大,退火处理后表面变得较粗糙,振动模式并未出现,说明结构破坏严重。     

椭圆型保偏光纤耦合器的研制

保偏光纤耦合器是干涉仪和光纤陀螺仪的关键器件。介绍了用匹配型椭圆包层保偏光纤制作保偏光纤耦合器的工艺流程、测试结果以及分光比随温度的变化情况。试验结果表明,保偏光纤耦合器的综合性能指标,尤其是附加损耗和温度性能达到了国内领先水平。     

采用罗戈夫斯基线圈诊断径向束流

 罗戈夫斯基线圈具有结构简单、高频特性好等特点而被广泛应用于脉冲电流测量。提出了用两个自积分式罗戈夫斯基线圈诊断径向束流的方法,在此基础上设计了两个用于径向束流诊断的自积分式罗戈夫斯基线圈,对其进行了标定。当标准电流的上升沿为30 ns时,罗氏线圈响应时间约为10 ns;整个系统的测量误差约为4.7%。从标定结果来看,该系统的频率响应特性和测量精度能够满足ns级束流诊断的要求,该方法可以用于径向结构高功率微波器件的束流强度测量。     

Metal–Organic Frameworks Based Electrocatalysts for the Oxygen Reduction Reaction

In view of the clean and sustainable energy, metal–organic frameworks (MOFs) based materials, including pristine MOFs, MOF composites, and their derivatives are emerging as unique electrocatalysts for oxygen reduction reaction (ORR). Thanks to their tunable compositions and diverse structures, efficient MOF-based materials provide new opportunities to accelerate the sluggish ORR at the cathode in fuel cells and metal–air batteries. This Minireview first provides some introduction of ORR and MOFs, followed by the classification of MOF-based electrocatalysts towards ORR. Recent breakthroughs in engineering MOF-based ORR electrocatalysts are highlighted with an emphasis on synthesis strategy, component, morphology, structure, electrocatalytic performance, and reaction mechanism. Finally, some current challenges and future perspectives for MOF-based ORR electrocatalysts are also discussed.     

浅谈少学时普通化学的教学方法

对于少学时普通化学课程,为保证教学质量,必须采用有针对性的教学措施。本文结合课题组教师多年的教学经验,介绍了几种行之有效的教学方法。     

上转换激光晶体研究进展

本文综述近年来晶体材料的上转换过程研究进展，介绍了上转换发光晶体材料研究中的一些新动向以及在室温环境下，掺杂稀土离子的晶体上转换激光运转的成功经验，列举了几种室温上转换激光器的泵浦条件、发射波长、以及转换效率等参数，说明晶体材料的上转换激光技术已趋于实用化。     

Scalable and Robust Bio-inspired Organogel Coating by Spraying Method Towards Dynamic Anti-scaling

Scaling usually causes serious problems in daily life and industrial production. Currently, developing passive anti-scaling coatings has shown promises to overcome this problem. In this work, we fabricated a scalable and robust bio-inspired organogel(BIO) coating, showing dynamic scale resistance in the oil/brine mixture. The oil layer of the BIO coating was utilized as a barrier to inhibit scale nucleation and reduce scale adhesion. The mechanical strength of the coating was optimized by regulating nanoparticle contents. Moreover, the universality of scale resistance was demonstrated by varying the types of nanoparticles, oils and scales. Compared with commercial pipeline materials, such as copper, this BIO coating significantly reduces scale deposition after 240-h scaling test(ca. 93% reduction). Therefore, this study designs scalable and robust organogel coatings for sustainable scale resistance, which may be used for practical application in oil production.     

Photo-Activated Circularly Polarized Luminescence Film Based on Aggregation-Induced Emission Copper(I) Cluster-Assembled Materials

In this study, a pair of chiral copper(I) cluster-assembled materials (R/S- 2 ) was prepared, exhibiting unique photo-response characteristics with a concentration-wavelength correlation property in DMSO solution. By the combination of R/S- 2 with a polymethyl methacrylate (PMMA) matrix, the first photo-activated circularly polarized luminescence (CPL) film was developed, the CPL signal (g_lum=9×10⁻³) of which could be induced by UV light irradiation. Moreover, the film exhibited a reversible photo-response and extremely good fatigue resistance. Mechanism study revealed that the photo-response properties of the R/S- 2 solution and film are attributed to the aggregation-induced emission (AIE) characteristics of R/S- 2 and a photo-induced deoxygenation process. This study enriches the types of luminescent cluster-assembled molecules and provides a new strategy for the construction of metal cluster-based stimuli-responsive composite materials.     

High Performance Dynamic X-ray Flexible Imaging Realized Using a Copper Iodide Cluster-Based MOF Microcrystal Scintillator

X-ray imaging technology has achieved important applications in many fields and has attracted extensive attentions. Dynamic X-ray flexible imaging for the real-time observation of the internal structure of complex materials is the most challenging type of X-ray imaging technology, which requires high-performance X-ray scintillators with high X-ray excited luminescence (XEL) efficiency as well as excellent processibility and stability. Here, a macrocyclic bridging ligand with aggregation-induced emission (AIE) feature was introduced for constructing a copper iodide cluster-based metal–organic framework (MOF) scintillator. This strategy endows the scintillator with high XEL efficiency and excellent chemical stability. Moreover, a regular rod-like microcrystal was prepared through the addition of polyvinyl pyrrolidone during the in situ synthesis process, which further enhanced the XEL and processibility of the scintillator. The microcrystal was used for the preparation of a scintillator screen with excellent flexibility and stability, which can be used for high-performance X-ray imaging in extremely humid environments. Furthermore, dynamic X-ray flexible imaging was realized for the first time. The internal structure of flexible objects was observed in real time with an ultrahigh resolution of 20 LP mm⁻¹.     

Highly Efficient Circularly Polarized Luminescence from Chiral Au13 Clusters Stabilized by Enantiopure Monodentate NHC Ligands

Chiral Au nanoclusters have promising application prospects in chiral sensing, asymmetric catalysis, and chiroptics. However, enantiopure superatomic homogold clusters with crystallographic structures emitting bright circularly polarized luminescence (CPL) remain challenging. In this study, we designed chiral N-heterocyclic carbenes (NHCs), and for the first time enantioselectively synthesized a pair of monovalent cationic superatomic Au₁₃ clusters. This new enantiomeric pair of clusters has a quasi-C₂ symmetric core and exhibited CPL with an unprecedent solution-state quantum yield (QY) of 61 % among those of the atomically precise Au nanoclusters. DFT calculations provided insights into the circular dichroism behavior, and revealed the origin of CPL from superatomic Au clusters. This work opens a new avenue for developing novel homochiral nanoclusters using chiral NHC ligands and provides fundamental understanding of the origin of the chiroptics of metal clusters.