从国际纳米技术标准的推出看科技新词语的选用

当今世界科学技术的高速发展正在产生大量新的科技词语,这些词语主要以英语形式在学术界传播。随着科技发展,一些学术机构正在对这些新科技词语的遴选、规范、应用进行研究。以纳米科技为例,国际标准化组织(the International Organization for Standardization,ISO)是协调各国标准化机构的国际联盟组织     

智能弗兰克-赫兹实验测量仪的研制

采用AT90S 8535单片机研制了一种智能弗兰克－赫兹实验测量仪，能测量10^-9-10^-12A微电流，提供0－50V线性程控稳压电源，模糊控温，图形液晶显示中英和曲线，曲线数据打印，具有测量快、精度高、体积小、成本低、使用方便等优点。本介绍了该测量仪的硬件组成、典型电路工作原理、软件设计，分析了实验结果。     

Importance of ligands on TiO_2 nanocrystals for perovskite solar cells

The fabrication of high-quality electron-selective layers at low temperature is a prerequisite to realizing efficient flexible and tandem perovskite solar cells(PSCs). A colloidal-quantum-dot ink that contains TiO_2 nanocrystals enables the deposition of a flat film with matched energy level for PSCs; however, the selection of ligands on the TiO_2 surface is still unexplored. Here, we systematically studied the effect of the titanium diisopropoxide bis(acetylacetonate)(TiAc_2)ligand on the performance of PSCs with a planar n-i-p architecture. We prepared TiO_2 nanocrystals from TiCl4 and ethyl alcohol with Cl~- ligands attached on its surface and we found that a tiny amount of TiAc_2 treatment of as-prepared TiO_2 nanocrystals in a mixed solution of chloroform and methyl alcohol can enhance PSC power conversion efficiency(PCE)from 14.7% to 18.3%. To investigate the effect of TiAc_2 ligand on PSCs, TiO_2 samples with different TiAc_2 content were prepared by adding TiAc_2 into the as-obtained TiO_2 nanocrystal solution. We use x-ray photoelectron spectroscopy to identify the content of Cl so as to reveal that Cl ligands can be substituted by TiAc_2. We speculate that the improvement in PCE originates from amorphous TiO_2 formation on the TiO_2 nanocrystal surface, whereby a single-molecule layer of amorphous TiO_2 facilitates charge transfer between the perovskite film and the TiO_2 electronic transport layer, but excessive TiAc_2 lowers the PSC performance dramatically. We further prove our hypothesis by x-ray diffraction measurements. We believe the PCE of PSCs can be further improved by carefully choosing the type and changing the content of surface ligands on TiO_2 nanocrystal.     

Defect-Related Photoresponse and Polarization-Sensitive Photodetection of Single ZnO Nanowires

Defect-related photoconductivity of single ZnO nanowires is investigated. The photoconductivity shows powerlaw dependence with incident green laser intensity due to the defect mechanisms including both recombination centres and traps. The device based on single ZnO nanowire shows a sensitive photoresponse to green light with significant on/off ratios. In addition, the photocurrent ＆ highly sensitive to the polarization of the incident illumination. Therefore, the nanowire may act as a polarized photodetector.     

阴极荧光在表面等离激元研究领域的应用

表面等离激元以其独特的光学性质广泛应用于纳米尺度的局域电磁场增强、超高分辨成像及微弱光电探测.阴极荧光是电子与物质相互作用而产生的光学响应,利用电子束激发金属纳米结构能够实现局域等离激元共振,并在亚波长尺度实现对共振模式的调控,具有超高空间分辨的成像特点.阴极荧光探测通常结合扫描电子显微镜或透射电子显微镜而实现,目前己被应用于表面等离激元的探测及共振模式的分析.本文从阴极荧光物理机理出发,综述了单一金属纳米结构和金属耦合结构的等离激元共振模式阴极荧光研究进展,并总结了阴极荧光与角分辨、时间分辨以及电子能量损失谱等关键技术相结合的应用,进一步分析了其面临的关键问题,最后展望了阴极荧光等离激元研究方向.     

第二届亚太地区近场光学研讨会在北京大学举行

由北京大学主持的第二届亚洲－太平洋地区近场光学国际研讨会（ＴｈｅＳｅｃｏｎｄＡｓｉａ－ＰａｃｉｆｉｃＷｏｒｋｓｈｏｐｏｎＮｅａｒ－ｆｉｅｌｄＯｐｔｉｃｓ）于１９９９年１０月２０日在北京大学新建的图书馆会议厅举行开幕式．来自日本、韩国、德国、瑞士、以色列、澳大利亚、加拿大、墨西哥等国家的代表与中国大陆、台湾、香港的同行共１００位近场光学专家和学者参加了为期三天的研讨会．北京大学常务副校长迟惠生教授致欢迎词,教育部、自然科学基金委员会的领导和北京大学甘子钊院士、清华大学金国藩院士等出席了开幕式．近…     

关于加强物理资助的对话

随着新冠疫苗接种的进行,人们似乎在新的一年看到希望.然而,新冠大流行造成的经济损失仍将持续数年.即使在经济繁荣时期,纯科学也难以得到资助,那么在经济恶化的情况下,依然如此吗?亚利桑那大学的Cherry Murray和英国爱丁堡大学的Nick Treanor对资助物理研究必要性进行对话.     

纳米集成光路中的光源、光波导和光增强

使用近场光学显微术(scanning near-field optical microscopy, SNOM)研究了ZnO亚微米线端面出射性质,不同空间形貌Ⅱ-Ⅵ族半导体荧光器件光波导特性,二维光子晶体、准晶光子晶体对LED的出射增强作用以及表面等离激元(surface plasmon polariton, SPP)与半导体纳米荧光器件的相互作用,对纳米集成光路中的光源、光波导、光增强三个重要问题做了实验和理论上的分析.研究发现半导体微纳米线端面出射光束的质量与样品的直径有密切关系.通过合理地设计其直径和 关键词： 纳米集成光路 扫描近场光学显微术 光波导 光增强     

SETUP AND APPLICATION OF SCANNING NEAR-FIELD OPTICAL MICROSCOPY

The research on the setup and application of scanning near-field optical microscopy (SNOM) performed in our laboratory is reviewed in this report. We have constructed a versatile low temperature scanning near-field optical microscope with the capability of near-field imaging and spectroscopy, operating at liquid nitrogen temperature. A special designed coaxial double lens was used to introduce the illumination beam through a 200μm fiber; the detected optical signal was transmitted via a fiber tip to an avalanche photon detector. The performance test shows the stability of the new design. The shear force image and optical image of a standard sample are shown. A system of SNOM working at room temperature and atmosphere was used to characterize semiconductors and bio-molecular samples. It revealed the unique features of semiconductor microdisks in the near-field that is significantly different from that of far-field. The effects of different geographic microstructures on the near-field light distribution of InGaP, GaN, and InGaN multi-quantum-well microdisk were observed.     

智能音箱与声音传感器

现代生活已经产生微妙变化.在节日期间,我们会与家中的智能音箱对话:"爱丽丝,请播放些圣诞歌曲","Google,请打开美妙的灯光","Siri,请问烤火鸡还需要多长时间出炉",就如同与家里成员一样对话,而这种无形的指令几乎是瞬时得到执行.